Mudlarking: Glass Treasures from the Thames
By Jason Sandy
The River Thames flowing through Central London (Jason Sandy).
On a cold, winter day in Roman Londinium in the 2nd century AD, Lucius headed to a local bathhouse along the River Thames. To display his wealth, he wore a beautiful, gold signet ring set with a stunning intaglio carved from green jasper. Upon arrival at the bathhouse, Lucius entered the Apodyterium (changing room) and got undressed. The ring was the only item he could wear to show his social status while enjoying the facilities. To warm up after the freezing walk to the bathhouse, Lucius went straight to the Caldarium (hot steam room), heated by a hypocaust (underfloor heating). After a half hour in the intense heat, he was sweating profusely and took a cold plunge bath in the Frigidarium (cold room), which was a shock to his system. To warm up again, he relaxed in the Tepidarium (warm room) where he used a strigil to exfoliate and remove the dead skin from his body. Completing his wellness routine, Lucius applied olive oil to replenish the moisture and rejuvenate his skin.
When he got home after several hours of relaxation and socializing with friends in the bathhouse, Lucius noticed that the intaglio in his ring was missing. Where could it be? He went back to the bathhouse to look for the intaglio, but unfortunately, it was nowhere to be found. The carved gemstone had probably been washed down the floor drain and into the pipework, which emptied into the nearby River Thames. While Lucius was in the steam room, the adhesive made from vegetable extracts used to secure the intaglio to the signet ring probably loosened in the hot, moist environment. When he took a cold plunge in the Frigidarium, the sudden change in temperature possibly caused the intaglio to shrink and fall out of the signet ring with the movement of Lucius’s hands as he was swimming.
Green jasper intaglio depicting the Roman god Sol racing a chariot (Ed Bucknall).
Around 1,800 years later, mudlark Ed Bucknall spotted the long-lost intaglio nestled among some pebbles on the Thames foreshore near a culvert or drain which emptied into the river, possibly from a former Roman bathhouse. When he looked closely, Ed could see a charioteer and horses. The green jasper gemstone was delicately carved with an image of the sun god, Sol, wearing a spiky crown which represents the sun’s rays. He is shown racing his chariot through the sky, pulled by four horses (quadriga), a symbol of triumph.
Although Lucius is a fictional character, someone like him could have lost this valuable gemstone intaglio in similar circumstances. This intaglio was definitely part of a signet ring worn by an important Roman who pressed the intaglio in soft clay or melted beeswax to seal a letter or official document circa 1,800 years ago. This extraordinary intaglio was on display in London Museum Docklands as part of an exhibition called “Secrets of the Thames: Mudlarking London’s Lost Treasures.”
According to Kate Sumnall, archaeological curator of the exhibition, over 30 different intaglios have been discovered by mudlarks in one specific area of the foreshore. Although we don’t know exactly how they were lost, Kate thinks that: “It’s possible the intaglios washed out of a drain from a bathhouse or something else which has gathered them together in a concentrated area. This is one possible explanation, but there are others as well.”
Red carnelian intaglio engraved with the Roman goddess Fortuna (London Museum).
This one location along the river has produced one of the greatest assemblages of Roman intaglios ever found in Britain. Similar deposits of intaglios have also been discovered in the Roman Baths in Bath, Caerleon Roman Baths in Wales, and two Roman bathhouses near Hadrian’s wall in Carlisle. The intaglios found in the Thames are made from a variety of different materials, including glass and semi-precious gemstones, such as carnelian, green jasper, yellow jasper, and nicolo onyx. Mudlark Jo Cook found one of the finest carnelian intaglios (above) carved with the image of the goddess Fortuna, holding a cornucopia (horn of plenty) representing abundance. Her hand rests on a rudder to show her control of destiny.
Left to right: Roman intaglio fresh from the Thames, yellow jasper intaglio carved with a scorpion, and red carnelian intaglio engraved with an abstract fish (Ed Bucknall).
Over the past ten years, Ed has discovered many Roman intaglios with different images, such as gods, goddesses, and animals.
Nicolo onyx intaglio set within iron ring (Ed Bucknall). Display of Roman intaglios in London Museum Docklands (London Museum).
One is still set in a ring (above) lost in the river in antiquity. Twelve of Ed’s best intaglios were on display in the exhibition (above right), along with examples found by other mudlarks.
Roman glass cubes (Ed Bucknall).
In the same area where the intaglios were discovered, mudlarks have also found a wide variety of colored glass from Roman times, washed up by the tidal river. These small shards of glass (above) were made in every color of the rainbow. According to Kate Sumnall, “These tiny cubes of colored glass were shipped to London, probably to be used in workshops making beads and enamel. Glass was produced where the raw materials were readily available. Egypt was one of the places where glass was manufactured in Roman times. These glass cubes may have been used as tesserae for mosaics on floors or walls, but they were also used for making glass beads or enamel, both of which were important trades in London at this time.” The glass cubes were also melted down and poured into small cells to decorate brooches which were fashionable in Roman Londinium.
Roman melon bead fresh from the Thames (Jason Sandy). Roman melon bead on display in London Museum Docklands (London Museum).
The Romans also loved wearing necklaces with large glass beads. They were experts in glassmaking and produced beautiful glass “melon” beads which have convex ribs around the circumference to catch the light. A few years ago, I found a large Roman melon bead (above left) which dates to AD 43–300. After being tumbled in the Thames for nearly two millennia, it now has a frosted greenish-grey color, but it would likely have been a transparent bluish-green glass bead when originally made. In the new mudlarking exhibition, several Roman melon beads (above right) were on display which were found in the same location as the one I found.
Left to right: Red and black tubular trade bead made by Sir Nicholas Crisp (London Museum). Blue, white, and red chevron bead produced in Murano, Italy (London Museum).
Other examples of glass beads featured in the exhibition were trade beads from the 17th century which have a horrible history. A few years ago, mudlark Malcolm Russell discovered a large black and red, tubular bead (above left). It was produced in a factory along the Thames owned by Sir Nicholas Crisp in Hammersmith, London. “Sir Nicholas Crisp’s factory produced mass quantities of these trade beads,” explains Kate. “He was a very wealthy merchant and key figure in the Royal African Society which was founded around 1660 by the king, royal family, and merchants who traded glass beads for gold, ivory, redwood, and enslaved people. They held the monopoly on the West African trade route. According to reports, the African communities valued the glass beads and wore them as symbols of status.”
Another glass trade bead on display in the exhibition was a large chevron bead (above right) produced by Venetian glassmakers in Murano, Italy between AD 1500 and the early 1600s. It was formed by forcing or blowing molten glass into a mold with striated edges which created the ridges on the outer surface. Additional layers of alternating blue, white, and red glass were added before it was quickly drawn into a six-foot-long cane. It was then cooled, cut into short pieces, and chamfered at both ends to create a unique, star-shaped pattern.
Left to right: Large Dutch bottle on display in London Museum Docklands (Jason Sandy). 18th-century mallet bottle (London Museum). Glass bottle seal with medieval figure (Alessio Checconi).
Within the exhibition, the largest glass bottle ever found in the river (above left) was proudly displayed on a custom-made pedestal. Dating to AD 1600–1650, this colossal bottle is a whopping 18.7 inches (475 mm) high and 15 inches (380 mm) wide. Made in Holland, it was used to transport wine to Britain. It’s an absolute miracle that this fragile bottle survived for centuries in the turbulent river conditions. When it was dropped, the bottle must have quickly been encapsulated by the soft, dense mud and protected before eroding out of the mud and discovered by a lucky mudlark over a hundred years ago.
Next to the large Dutch bottle, an 18th-century mallet bottle (above center) appeared alongside an unusual bottle seal (above right) found by mudlark Alessio Checconi. The seal is made of molten glass which was stamped and attached to the side of a bottle. On the seal, a medieval male bust is depicted with long hair, circular cheeks, and a frowning facial expression. Does this image represent a specific person, or is it perhaps the logo of the company which produced the wine or the bottle?
“Secrets of the Thames” mudlarking exhibition in London Museum Docklands (London Museum). Recreation of the Thames foreshore in the gallery (Jason Sandy).
“Secrets of the Thames” exhibition was in London Museum Docklands, located in an early 19th-century sugar warehouse in the West India Docks of Canary Wharf. Within the original timber structure of the historic warehouse, the Thames foreshore has been recreated in the shape of mounds, meandering through the gallery space.
Among the pebbles and debris, hundreds of authentic mudlarking finds were waiting to be discovered. Each time I visited the exhibition, I spent more time staring at the foreshore than at the objects in the glass vitrines, hoping to spot another artifact camouflaged in the Thames terrain. Unlike traditional exhibitions, this experiential way of engaging with the artifacts was revolutionary.
For more information about other exhibitions, visit London Museum’s website at www.londonmuseum.org.uk.
Learn more about mudlarking
Learn more about the experiences of mudlarks, who search the shores of rivers, bays, and seas for historical finds and other objects. Articles ›
Mudlarking on the Thames Foreshore requires a permit. Learn about rules for mudlarking in London ›
This article appeared in Beachcombing Magazine Volume 50 September/October 2025.
