What London Reveals When the Thames Goes Out

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Twice a day, the Thames does something remarkable. The tide pulls back and exposes a strip of riverbed — sometimes just a few metres wide, sometimes stretching far out from the wall — that most Londoners never notice. That strip is called the foreshore, and it holds more history per square metre than almost anywhere in Britain.

The River Thames has been London’s backbone for over 2,000 years. Romans crossed it, medieval merchants traded along it, and Victorians dumped almost everything into it. What the river absorbed, it also preserved. Every low tide pulls that history back to the surface.

How the Thames Tide Works

The Thames is tidal as far inland as Teddington Lock, about 19 miles upstream from the open sea. Below that lock, the river rises and falls with the tides twice a day. In central London, the tidal range — the difference between high and low water — is roughly six to seven metres at London Bridge.

Low tide happens approximately every 12.5 hours. Tide tables are published by the Port of London Authority (PLA) at pla.co.uk — search for “Thames tides” and select your nearest gauge. Aim to arrive on the foreshore about 30 to 45 minutes before the lowest point of the tide. That gives you the most time and the widest stretch of exposed riverbed before the water returns.

The water comes back faster than most people expect. The PLA advises always watching the tide and having a clear exit route before you go down to the foreshore. Never stand with your back to the river.

What People Find on the Foreshore

The foreshore holds artefacts from every period of London’s past. Common finds include:

• Clay tobacco pipes: Mass-produced from the 17th to early 20th century, these are among the most common finds. The shape of the bowl changed over time, which helps date a pipe to within a few decades.
• Roman pottery: Fragments of amphorae, Samian ware, and other Roman ceramics turn up regularly near Queenhithe and Bankside, both of which were key Roman sites.
• Medieval floor tiles: Decorated glazed tiles from the 13th to 15th centuries, washed into the river from demolished buildings along the bank.
• Victorian glass and ceramics: Old medicine bottles, ink bottles, stoneware jars, and transfer-printed pottery from the 19th century are extremely common throughout the foreshore.
• Animal bones: Butchered bones from medieval and later kitchens appear everywhere. They tell you a great deal about what Londoners were eating hundreds of years ago.
• Coins: Rare but not impossible. Medieval silver pennies, Georgian copper coins, and Roman coins have all been recorded from the foreshore.
• Ship components: Iron bolts, copper sheathing from wooden hulls, and fragments of rope and rigging from the river’s long working life.

In recent years, the foreshore has also yielded more unusual finds. A Bronze Age timber trackway was found near Vauxhall. Saxon and Viking-era artefacts have appeared at Billingsgate. A 2,500-year-old Bronze Age sword was discovered near Westminster Bridge in 2019.

You Need a Permit to Search

The Thames foreshore is not public land in the way that a park is. Most of it belongs to the Crown Estate and is managed by the PLA. To search the foreshore and remove any finds, you need a permit.

The PLA issues two types of foreshore permit:

• Standard Permit: Free. Allows surface searching only — no digging, no tools. You can pick up items that are already exposed by the tide. This is the right starting point for most people.
• Special Permit: Currently £50 per year. Allows digging to a depth of 7.5cm using a hand trowel. Requires evidence of experience and a basic understanding of archaeological recording.

Apply at pla.co.uk/pleasures/mudlarking. The application is straightforward and turnaround is usually quick. Children under 13 can accompany a permit holder but cannot hold their own permit.

Significant finds — anything made of precious metal, prehistoric, or clearly of historical importance — must be reported. The Portable Antiquities Scheme (PAS) database, run by the British Museum, is where finds are recorded. Some objects may fall under the Treasure Act 1996, which requires reporting to the local coroner.

Where to Access the Thames Foreshore

There are public access points to the foreshore along the river’s length. Not every stretch is reachable — some sections have high walls with no steps — but several spots are well established:

• Queenhithe, City of London: One of the oldest docks in London, dating back to Saxon times. The foreshore here is particularly rich in medieval finds. Access via the small dock off Upper Thames Street.
• Bankside, Southwark: The south bank near Shakespeare’s Globe. Steps down to the foreshore are visible from the riverside walk. Roman Southwark means finds from 2,000 years ago are possible here.
• Gabriel’s Wharf, South Bank: Good access, manageable foreshore width at low tide, and a central location.
• Strand on the Green, Chiswick: A quieter stretch further upstream. Good access at low tide, with the riverbank path running alongside.
• Putney Bridge: Steps down from the north side of the bridge. Good access and a stretch that is less picked over than central London.
• Richmond: Further upstream. The foreshore is wider and the finds tend to be post-medieval, but it is an accessible and pleasant stretch for first-timers.

The Society of Thames Mudlarks — one of the longest-established foreshore search groups in the country — has a waiting list for full membership, but their website is a useful resource for understanding which areas have been most productive over the years.

What to Bring

The foreshore is muddy, sometimes gravelly, and always wet underfoot. Preparation makes the difference between an enjoyable outing and a miserable one.

• Wellies or waterproof boots: Essential. The mud can be deep in some sections. Ankle-height waterproof boots are the minimum; knee-high wellies are better in softer spots.
• Old clothes: You will get muddy. Wear something you do not mind ruining.
• Gloves: The foreshore contains broken glass, sharp metal, and old waste. Rubber-palmed work gloves are strongly recommended.
• A bag for finds: A small cotton or mesh bag to carry anything you want to examine more closely. Avoid plastic if you plan to photograph finds later — condensation makes images difficult.
• A phone with the tide table: Know when the water is coming back. The PLA tide gauge data is available as an app and online.
• Hand sanitiser and a wet wipe: You will want to clean your hands before you touch your phone or eat anything.

Recording and Identifying What You Find

When you find something interesting on the foreshore, photograph it before you pick it up. Note the location — ideally using the what3words app or a GPS coordinate — and note the context: was it in the gravel, in the mud, or in a layer of black silt?

The Museum of London’s series on Thames foreshore finds is an excellent reference for identification. The books are out of print but available through libraries and second-hand dealers. The PAS database at finds.org.uk allows you to search recorded finds by type and location, which helps you understand what has already been found in the stretch you are searching.

The London Museum — formerly the Museum of London, now relocated to West Smithfield — holds one of the largest collections of Thames foreshore finds in the world. Their online collection database includes thousands of objects and is free to access. It is worth spending an hour browsing it before your first foreshore visit. It helps you recognise what you are looking at when the real thing is in your hand.

Getting the Timing Right

Experienced foreshore searchers will tell you that the best moment is not always dead low tide. The last 30 minutes before low tide — when the water is still retreating and the mud is glistening but firm — can be particularly productive. Material that has been loose on the riverbed gets moved by the current and settles just as the tide turns.

After heavy rain, the river runs faster and higher, and when it drops back, the foreshore sometimes holds newly exposed material that had been buried under sediment. Searching after a significant rainfall and subsequent drop in river level is a tactic that many mudlarks use.

Winter tides are often lower than summer tides, which means more foreshore is exposed. The coldest months — January and February — can produce the best access, though the conditions underfoot are harder and the days shorter.

A Living Record of the City

What makes the Thames foreshore unlike any other historical site in London is that it changes every day. The river moves its contents constantly. A section that yielded nothing last month might produce something remarkable this week. There is no map you can follow — only time, attention, and a willingness to look carefully at what the river leaves behind.

For a city as layered as London, that is fitting. Two thousand years of people have used this river to build, trade, travel, and survive. The Thames has kept a record of all of it. Twice a day, it opens that record to anyone willing to put on a pair of wellies and go and look.

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