British glass is often identified backwards. A seller starts with a colour, a familiar shape or a confident attribution, then looks for evidence to support the name. Collectors get better results by doing the opposite: record how the piece was made, inspect the base, transcribe every number or mark, identify the glass type, and only then compare the object with documented factory patterns.
That matters because many important British factories produced large quantities of unmarked glass. Whitefriars is the obvious example, but the same problem appears with Bagley, Sowerby, Davidson, Jobling and Scottish art glass. A polished pontil, a mould seam or a green UV reaction can be useful evidence; none is a maker's signature by itself.
This guide concentrates on British names regularly encountered by UK collectors, from Victorian pressed and cameo glass to twentieth-century art glass and paperweights. It also corrects several persistent online shortcuts: Bagley was at Knottingley, not Castleford; an RD number dates registration of a design, not manufacture of your individual object; and Thomas Webb made Queen's Burmese in England under the Mount Washington process rather than inventing and patenting it independently in 1885.
If fluorescence is the main clue on your piece, use our UK uranium glass identification guide and UV-reactive glass guide alongside this maker reference. The chemistry can narrow the search, but attribution still needs design evidence.
A practical evidence order for identifying British glass
- Photograph the whole object and base. Include the rim, foot, handle or stopper, mould seams and any ground or polished area.
- Transcribe marks exactly. Record acid-etched signatures, embossed factory devices, paper labels, pattern numbers and every "Rd", "Regd" or registration number before cleaning.
- Decide how it was formed. Pressed glass normally shows mould construction; blown glass may show a pontil scar or a finished base; mould-blown glass can combine characteristics of both.
- Record colour in daylight. Factory colour names can matter, particularly with Whitefriars, but colour should support a catalogue match rather than replace one.
- Check a catalogue, museum record or registered design. A silhouette match becomes much stronger when dimensions, rim, base, decoration and colour also agree.
- Use UV as a composition clue. Uranium, manganese, cadmium and selenium reactions can be informative, but fluorescence does not identify a factory.
Collector rule: one feature suggests; several independent features corroborate. A polished pontil is not "Whitefriars", a peacock mark is not automatically a date, and a registration number is not the year the object left the factory.
British glass makers: master identification table
| Maker | Location and collector period | Key products | Marks and identifiers | Typical UK value range |
|---|---|---|---|---|
| Sowerby | Gateshead. John Sowerby's Stamped Glass Works began in 1846; the Ellison Glass Works followed in 1852. The factory was taken over in 1957 and closed in 1972. | Victorian pressed glass, Vitro-Porcelain, coloured decorative ware, later carnival and Art Deco glass | Embossed peacock trademark on some pieces; moulded pattern/RD numbers; catalogue pattern matches | Common pieces about £10–£40; better Victorian colours, scarce patterns and documented designs often £50–£200+ |
| Bagley & Co. | Knottingley, West Yorkshire. Founded 1871; bought by Jackson Brothers in 1962, with later ownership changes. | Pressed domestic glass, Art Deco dressing-table ware, flower sets, Jetique, Bamboo and coloured/uranium examples | Many pieces unmarked; moulded numbers or wording occur; pattern-book silhouette, size and colour are important | Common pressed pieces £10–£40; better figural, uranium, rare-colour or complete sets often £40–£150+ |
| George Davidson & Co. | Teams, Gateshead. Founded 1867; Davidson name continued until the works changed ownership/name in the 1960s. | Pearline, Cloud Glass, Jade and pressed table/decorative glass | Lion-and-crown trademark on some wares; RD numbers; labels and documented pattern forms | Common pieces £15–£60; stronger Cloud/Pearline colours and scarce forms commonly £60–£180+ |
| James Powell & Sons / Whitefriars | London, then Wealdstone from 1923; Powell acquired the Whitefriars glasshouse in 1834. Factory closed 1980. | Arts & Crafts glass, tableware and Geoffrey Baxter textured designs including Bark, Banjo and Drunken Bricklayer | Paper labels on some pieces; many unmarked. Catalogue pattern, factory colour, dimensions and base finishing are critical | Ordinary pieces £30–£150; many sought Baxter forms £150–£500; rare large forms/colours can exceed £1,000 |
| Thomas Webb & Sons | Stourbridge area, nineteenth and twentieth centuries | Cut and engraved crystal, cameo glass, rock-crystal-style engraving, Queen's Burmese | Acid-etched or impressed Webb marks on some pieces; exact registered designs and documented decorative techniques | Later table glass may be £30–£120; fine Victorian cameo and Queen's Burmese often £150–£600+, with exceptional work much higher |
| Monart | John Moncrieff's North British Glassworks, Perth, principally 1924–1961 | Handmade mottled art glass, vases, bowls and lamps associated with Salvador Ysart and family | Paper labels can carry shape/colour codes; base and pontil construction are important. Labels alone are not proof. | Many vases £80–£300; large, rare, labelled or unusual forms can reach £400–£1,500+ |
| Vasart / Strathearn | Perth. The Ysart family established Vasart in 1946; Strathearn succeeded it in the 1960s. | Scottish art glass, mottled decorative ware and paperweights | Labels, base treatment, colour construction and documented shapes | Typical decorative forms often £30–£150; specialist paperweights and well-documented pieces can be substantially higher |
| James A. Jobling & Co. | Sunderland. Jobling's operation developed from the former Greener works; British PYREX production began under licence in 1921. | PYREX oven/laboratory ware, opalescent Art Deco bowls, figures and decorative pressed glass | JP/Jobling PYREX marks on heat-resistant ware; decorative pieces may carry moulded RD numbers and pattern evidence | Common decorative bowls £20–£60; better opalescent figures and scarce designs often £80–£200+ |
| Caithness Glass | Founded at Wick, Scotland, in 1961; later Oban and Perth production; brand now operates from Crieff. | Paperweights, engraved glass and decorative Scottish glass | Many paperweights acid-etched or engraved Caithness / Caithness Scotland; limited editions may add title and edition data | Common paperweights about £10–£30; boxed, limited and scarcer designs often £30–£150+, with specialist exceptions |
These values are broad UK secondary-market indications, not retail promises. Factory name alone is a poor valuation method. A common Caithness weight may sell for tens of pounds, while a large scarce-colour Whitefriars Drunken Bricklayer can move into four figures. Condition, size, colour, documented pattern, label, stopper and provenance can matter more than the maker heading.
Sowerby: pressed glass, the peacock and registered designs
John Sowerby established the Gateshead Stamped Glass Works in 1846, with the Ellison Glass Works following in 1852. By the later nineteenth century the firm was producing a vast range of pressed domestic and ornamental glass. Its Vitro-Porcelain range dates from the 1870s, while later production included carnival and Art Deco designs.
The embossed peacock trademark is a strong factory clue when genuinely moulded into a piece, but it was not applied universally. Pattern numbers and British registered-design numbers can be more useful. A Sowerby attribution is strongest when mark, pattern, dimensions and period colour all agree.
Opaque Sowerby glass can be mistaken for ceramic material in photographs, while coloured transparent and slag-like effects overlap visually with other north-east factories. Do not identify by colour effect alone.
Bagley: Knottingley, not Castleford
Wakefield Museums records William Bagley founding Bagley & Co. at Knottingley in 1871. Castleford is close and has its own important glass history, which probably explains the persistent online description "Bagley of Castleford", but it is not the factory location.
Bagley moved from bottles into a major decorative pressed-glass trade. Inter-war pieces are particularly collectable, including bold geometric and figural forms and uranium-bearing green glass. The same mould can occur in several colours, so fluorescence does not establish the maker.
Pattern 8833 is a useful example of the right attribution method: the six-fluted vase is documented under Bagley's catalogue number 8833 and registered design 785064, registered on 21 July 1933. Known examples occur in several colours, including uranium green. Shape and registration identify the design; UV describes the glass formulation.
Davidson: Pearline, Cloud Glass and registered designs
George Davidson founded the Teams Flint Glass Works at Gateshead in 1867. The firm became a major pressed-glass producer and introduced its best-known Pearline treatment in 1889. Blue and lemon-yellow Pearline have characteristic heat-treated opaque or opalescent edges, and registered-design numbers are particularly useful on surviving examples.
Davidson's Cloud Glass belongs to the 1920s and later inter-war period. Specialist references date the development to the early 1920s, with production using a darker colour streaked through a lighter body to create a clouded effect. The look is distinctive but not exclusive enough to identify an unrecorded shape by colour alone.
Lemon Pearline is uranium-bearing and fluoresces green under UV. That is a composition clue, not a Davidson signature: other factories also used uranium recipes.
Whitefriars: identify the pattern before the colour
James Powell acquired the Whitefriars glasshouse in London in 1834. Production moved to Wealdstone in 1923, and the factory finally closed in 1980. The Whitefriars name now attracts enough money that misattribution is common.
Geoffrey Baxter joined the design team in 1954. His textured range entered production in 1967 and includes some of the factory's best-known collector forms: Bark, Banjo and Drunken Bricklayer among them. Factory colours and pattern numbers are valuable research tools, but most pattern numbers are catalogue references rather than moulded marks on the vase.
For an unlabelled Whitefriars attribution, look for:
- an exact documented catalogue form;
- correct dimensions and proportions;
- a factory colour documented for that pattern and period;
- base finishing and construction consistent with authenticated examples;
- and, where present, a credible period label.
A polished pontil is not enough. Scandinavian, Czech, Italian and other British factories made heavy, textured and cased glass that can look convincingly Whitefriars in a single photograph.
Thomas Webb: Stourbridge skill and the Queen's Burmese correction
Thomas Webb & Sons is associated with fine Stourbridge work including cut crystal, engraved glass and cameo glass. Attribution relies heavily on execution, documented designs and marks where present; it should not be approached with the same rules used for mass-produced pressed glass.
A persistent shortcut says that Thomas Webb "patented Queen's Burmese in 1885". The sequence is more complicated. Burmese glass was developed by Frederick Shirley at the Mount Washington Glass Company in the United States and patented there in 1885. Webb subsequently made Queen's Burmese in England under the protected process. Corning Museum examples by Thomas Webb date from about 1886 onward and can carry impressed wording including "Queen's Burmese Ware Patented".
The word patented on a Webb object therefore does not mean Webb invented the formula. This is exactly the kind of detail that separates object evidence from simplified dealer lore.
Monart, Vasart and Strathearn: keep the Perth lineage straight
Monart was made at John Moncrieff's North British Glassworks in Perth, principally from 1924 to 1961, with Salvador Ysart and his family central to its development. Strong colour, mottling, bubbles and aventurine can appear, but no one visual recipe identifies Monart.
Salvador Ysart and family members left Moncrieff to establish Vasart in 1946. Strathearn later succeeded Vasart in the 1960s. Related techniques and family connections explain the visual overlap, but they do not make the brands interchangeable.
Original Monart labels can carry shape and colour codes and are useful evidence, but labels can be transferred. Base and pontil construction, exact shape and established Ysart references should agree with the label before a high-value attribution is accepted.
Some secondary lists refer to a separate maker called Kinglass in this context. We have not found sufficiently reliable museum, archive or established specialist evidence to treat "Kinglass" as a documented British glassmaker in the same lineage. Rather than invent a history to fill a checklist, it is omitted here pending verifiable evidence.
Jobling: Sunderland art glass and British PYREX
James A. Jobling & Co. connects decorative glass with industrial and domestic heat-resistant ware. In 1921 the Sunderland firm obtained the licence to manufacture and market PYREX in Great Britain and much of the Empire. Science Museum Group collections include Sunderland Jobling PYREX with the JP monogram and "PYREX MADE IN ENGLAND" wording.
Jobling is equally important to Art Deco collectors for pressed and opalescent decorative designs from the 1930s. Bowls, figures and flower-related designs can carry registered-design numbers that provide strong attribution evidence.
Do not assume that every PYREX-marked object belongs to the decorative-art market, or that every anonymous opalescent bowl is Jobling. Exact function and pattern matter.
Caithness: marks, editions and paperweights
Caithness Glass was founded at Wick in 1961 by Robin Sinclair. The company's own history records that paperweight development followed soon afterwards, with Paul Ysart contributing early expertise and Colin Terris helping establish large-scale modern paperweight production later in the 1960s.
Many Caithness paperweights are unusually cooperative for collectors because bases can carry engraved or acid-etched factory marks, titles and edition information. Box and certificate can help, but "limited edition" is not automatically synonymous with rare or expensive; edition size and current demand still matter.
How to identify British glass with no maker's mark
| Feature | What it can tell you | Makers or groups to check | Confidence on its own |
|---|---|---|---|
| Embossed peacock device | Strong Sowerby factory evidence if moulded as part of the original object | Sowerby | High for maker; low for exact date without pattern research |
| Lion-and-crown factory device | Documented Davidson clue on relevant pressed wares | George Davidson & Co. | High when genuine and period-consistent |
| Moulded RD / Regd number | Can identify a British registered design and establish a not-before registration date | Sowerby, Jobling, Davidson, Webb and many others | High once traced; number alone is not a maker name |
| Heavy textured geometric vase with polished base | Possible Baxter-era route | Whitefriars plus British and continental lookalikes | Low until exact pattern, size and colour agree |
| Clouded/swirl colour in a documented pressed form | Potential Davidson Cloud Glass evidence | Davidson first, then contemporary competitors | Medium only with pattern match |
| Art Deco pressed figure or flower-set form | Can narrow to an inter-war pattern family | Bagley, Jobling, Sowerby, Davidson | Low without dimensions/pattern; high with exact catalogue match |
| Mottled blown glass with controlled bubbles/aventurine and characteristic base | Useful Scottish art-glass evidence | Monart, Vasart, Strathearn and related makers | Medium; authenticated shape/base comparison required |
| Caithness factory mark plus title/edition data | Usually direct manufacturer and edition evidence | Caithness | High, subject to normal authenticity checks |
| Bright green, orange or pink fluorescence under UV | Evidence about glass chemistry | Potentially many makers | Very low for maker attribution |
What does an RD number on glass mean?
British registered design numbers are among the best dating tools available to glass collectors, but they are routinely overstated. "Rd No", "Regd" or similar wording refers to registration of a design. Once the number is traced, it can establish the registrant and registration date.
That date is normally a terminus post quem: the object should not pre-date the protected design. It does not prove that your individual example was manufactured in that year. Successful patterns could remain in production for years, and moulds could continue under later ownership.
Use the number in three stages: transcribe it exactly; find a reputable registration record; then compare the registered design or known pattern with the physical object. Do not infer a maker from a number copied from a marketplace listing.
Which British makers used uranium glass?
Documented uranium-bearing glass exists from several British factories, including Bagley, Sowerby, Davidson and Jobling-related production. The important distinction is that uranium is an ingredient, not a brand. It cannot distinguish two factories that used similar formulations or colours.
A 365 nm or 395 nm UV torch can help document fluorescence, but the maker should still come from pattern, mark, registered design, dimensions or provenance. The same caution applies to manganese, cadmium and selenium reactions.
British glass values in the UK: 2026 guide
Price guides age quickly, so these are broad bands drawn from the current UK secondary and auction market. Auction hammer prices can be lower than dealer retail and normally exclude buyer's premium. Damage, married stoppers, polished rims and incorrect attribution can alter the value dramatically.
| Maker / type | Common collector range | Better / scarcer range | What drives the premium |
|---|---|---|---|
| Sowerby pressed glass | £10–£40 | £50–£200+ | Victorian date, unusual colour, Vitro-Porcelain, documented pattern/RD, condition |
| Bagley pressed glass | £10–£40 | £40–£150+ | Complete sets, figural forms, uranium colour, rare pattern/colour |
| Davidson | £15–£60 | £60–£180+ | Strong Cloud/Pearline colour, scarce form, matched sets, documented pattern |
| Whitefriars | £30–£150 | £150–£500 for many sought Baxter pieces; £1,000+ for exceptional combinations | Pattern, size, factory colour, rarity, condition and provenance |
| Thomas Webb | £30–£120 | £150–£600+ for many fine Victorian decorative pieces | Cameo quality, engraver/designer, Queen's Burmese, signature and provenance |
| Monart | £80–£300 | £400–£1,500+ | Large/rare shape, colour code, original label, lamp forms, provenance |
| Jobling decorative glass | £20–£60 | £80–£200+ | Opalescence, figural forms, scarce registered designs, condition |
| Caithness paperweights | £10–£30 | £30–£150+ | Scarce edition, designer, box/certificate, edition size and condition |
Whitefriars demonstrates why the top auction result for a maker must not become the baseline for everything with that name. Large Drunken Bricklayer vases in scarce colours can reach four figures; ordinary genuine Whitefriars can sell for a fraction of that. Identify the exact pattern, size and colour before comparing prices.
Common attribution mistakes
"It has a polished pontil, so it is Whitefriars"
No. Many glasshouses polished or finished bases. Whitefriars needs a compatible documented form, dimensions, colour and construction.
"It glows green, so it is Bagley or Sowerby"
No. UV behaviour describes chemistry. It cannot name the factory.
"The RD number dates my piece exactly"
No. It dates registration of the design; manufacture may be later.
"A Monart label proves Monart"
Not by itself. Labels can be transferred. Shape, colour code, base and known construction should agree.
"Any chunky 1960s/70s vase is Whitefriars"
No. Scandinavian, Czech, Italian and other British factories made heavy textured or cased forms. Catalogue comparison should come before the maker premium.
Condition: what matters on collectable glass
- Rim and foot chips: inspect under angled light; tiny bites disappear in listing photographs.
- Internal cracks: distinguish deliberate bubbles and tooling lines from damage travelling through the body.
- Clouding and dishwasher bloom: permanent surface damage can substantially reduce value.
- Ground stoppers: check that a decanter stopper is the correct fit and pattern.
- Labels: photograph original paper labels before cleaning and never soak them.
- Polished damage: a ground rim can remove a chip but alter the documented height and profile.
Frequently asked questions
How can I identify unmarked British glass?
Start with manufacturing method, base finish, dimensions, colour and any moulded numbers, then compare the complete form with factory catalogues and museum records. A single feature such as a polished pontil or UV glow is not enough.
What are RD numbers on glass?
RD or Regd numbers refer to British registered designs. They can identify who registered a design and when, but do not prove that an individual object was manufactured in that same year.
Which British glass makers used uranium?
Documented uranium-bearing pieces exist from Bagley, Sowerby, Davidson and Jobling among others. Fluorescence is a material clue, so combine it with a pattern, mark or registration.
How much is Whitefriars glass worth?
Many genuine pieces trade from roughly £30 into the low hundreds, while sought-after Geoffrey Baxter forms can reach several hundred pounds. Rare large forms in desirable colours can exceed £1,000.
What is Monart glass and who made it?
Monart was decorative art glass made at John Moncrieff's North British Glassworks in Perth, principally from 1924 to 1961, with Salvador Ysart and his family central to its development.
Are Sowerby and Bagley the same company?
No. Sowerby was a Gateshead glassmaker with roots in the 1840s; Bagley was founded at Knottingley in 1871. Their pressed-glass output can overlap stylistically, so pattern research matters.
How do I know if a Whitefriars vase is genuine?
Match it to a documented Whitefriars pattern, dimensions and period colour, then compare construction and base finishing with authenticated examples. A label is helpful but not conclusive on its own.
Does an original label make British glass more valuable?
An intact period label can strengthen provenance and add desirability, especially on art glass. It does not rescue a shape or colour that conflicts with the claimed factory.
Buy the evidence, not the attribution
British glass collecting becomes easier once the maker name is treated as a conclusion rather than a starting point. Photograph the base, record every number, identify the construction, then use museum records, registered designs and catalogues to test the attribution. That method works on a £15 pressed bowl just as well as on a four-figure Whitefriars vase.
Browse our current vintage and collectable stock, or use the uranium and UV-reactive guides above when fluorescence is the clue that brought you here.