Twice a day the Thames drops far enough to expose a strip of foreshore along much of central London. That strip is, in effect, the longest archaeological site in Britain, and searching it is called mudlarking.
Why so much survives
Thames mud is anaerobic — dense, waterlogged and almost oxygen-free. Bacteria that would normally rot organic material cannot function in it, so leather shoes, wooden objects, textiles, bone and rope survive for centuries in a way they simply do not on dry land.
The river has also been London’s dustbin, highway, sewer and shrine for two thousand years. Things fell in, were thrown in, were deliberately deposited as offerings, and are still there.
What people find
- Clay pipes — by far the commonest find. Seventeenth and eighteenth-century smokers used them once and threw them in the river, and the broken stems are everywhere. The bowl size roughly dates them: small bowls are early, when tobacco was expensive.
- Tudor dress pins — tiny brass pins used to fasten clothing, in enormous quantities.
- Pottery — from Roman Samian ware to Victorian transfer-printed china.
- Coins and tokens, from Roman to modern.
- Pilgrim badges — lead souvenirs from medieval shrines, thrown into the river as offerings.
- Leather shoes, sometimes complete, from the medieval period.
- Occasionally something genuinely remarkable — a Bronze Age weapon, a medieval sword, a gold ring.
The original mudlarks
The word is Victorian and it described real poverty. Mudlarks were among the poorest people in London — usually children and elderly women — who scavenged the foreshore for coal, rope, copper nails and anything sellable, working barefoot in filthy water at a time when the Thames was an open sewer.
Henry Mayhew documented them in London Labour and the London Poor in the 1850s, and his interviews make it clear this was a survival occupation of the last resort rather than anything romantic.
You need a permit
This is not optional and it is enforced. The Thames foreshore belongs to the Port of London Authority, and searching it — including simply picking things up — requires a permit.
Demand became so heavy after mudlarking was popularised on social media that the PLA suspended new permits entirely for a period, and availability has been restricted since. Digging is prohibited under standard permits; only surface searching is allowed, precisely because uncontrolled digging destroys the archaeological context that makes a find meaningful.
Anything of potential historical significance must be reported to the Portable Antiquities Scheme at the Museum of London, and finds meeting the legal definition of treasure must be declared.
The dangers
Real, and underestimated. The Thames is tidal and rises fast, and people have been cut off on the foreshore. Access is by a limited number of stairs, some of them slippery and unlit. The mud can be deep enough to trap a leg, and there is broken glass, rusted metal and sewage outfall.
Check tide tables, know where your exit is, go with someone, and wash your hands thoroughly afterwards. Guided walks with licensed mudlarks are the sensible way to start.