River Thames

• 1. Introduction

  ›

  The River Thames has carried more history than almost any waterway on earth. At 215 miles long, it is the longest river entirely within England, winding from a quiet field in Gloucestershire to the open North Sea near Tilbury and Gravesend. In 1929, John Burns, a one-time member of parliament for Battersea, was challenged by an American who thought the Mississippi the greater river. Burns replied: "The Thames is liquid history." That phrase has stuck. What does it mean for a river to be history? How does a body of water shape an empire, freeze solid in winter, sicken a city, and then clean itself up enough to win the world's largest environmental prize? Those are the questions this documentary will follow, from the river's ancient bed to the tunnel now snaking 25 kilometres beneath its tidal floor.

• 2. A Name From the Dark

  ›

  Tamesas: that is the Brittonic word from which every version of the river's name descends. Scholars Mallory and Adams trace it through Middle English as Temese, into Latin as Tamesis, and out the other side into modern Welsh Tafwys. The name element Tam is thought to have meant "dark," a quality it shares with Sanskrit tamas, Lithuanian tamsi, and the Welsh word tywyll. Kenneth H. Jackson argued the name is not Indo-European at all and that its meaning remains unknown. Peter Kitson pushed back, suggesting an Indo-European root meaning "muddiness" from a term meaning "melt." A Roman potsherd found at Oxford bears the inscription Tamesubugus fecit, meaning "Tamesubugus made this," and the craftsman's own name appears to be derived from the river's. The Ravenna Cosmography, compiled around AD 700, lists Tamese not as a river but as a place. A form of the name also appears in Magna Carta of 1215, written there as Tamisiam. The same root gave names to a cluster of British rivers: the Tamar on the border of Devon and Cornwall, several rivers called Tame in the Midlands and North Yorkshire, the Tavy on Dartmoor, the Teviot in the Scottish Borders, and the Thame, a direct tributary. Sculptor Anne Seymour Damer captured both identities of the river in a pair of works titled Tamesis and Isis, now on show at the River and Rowing Museum in Henley, having first been exhibited at the Royal Academy in London in 1785.

• 3. Fifty-Eight Million Years in the Making

  ›

  Researchers have identified the Thames as a discrete drainage line flowing as early as 58 million years ago, in the Thanetian stage of the late Palaeocene. For most of that time the river took a radically different route. Until around 500,000 years ago it turned north-east through Hertfordshire and East Anglia, reaching the North Sea near present-day Ipswich rather than near Tilbury. About 450,000 years ago, in the most extreme Ice Age of the Pleistocene, known as the Anglian glaciation, an ice sheet pushed as far south as Hornchurch in east London and the Vale of St Albans. The ice dammed the river in Hertfordshire and created large ice lakes; when those lakes burst, the river was forced south onto roughly the course it follows today. The ice lobe that stopped at present-day Finchley deposited about 14 metres of boulder clay and sent meltwater surging through the Finchley Gap, carving the Brent Valley in the process. At the height of the last ice age, around 20,000 BC, Britain was still connected to mainland Europe by the land mass known as Doggerland in the southern North Sea basin. The Thames did not flow into Doggerland at that point; instead it turned south from the eastern Essex coast and joined the proto-Rhine, Meuse and Scheldt rivers in a single watercourse called the Channel River, draining westward into the Atlantic through what would later become the Dover Strait. The overspill of a freshwater lake in the southern North Sea basin eventually broke open that gap. The bedrock beneath the Vale of Aylesbury is largely clay and chalk formed at the end of the ice age, when the area lay under the ancient proto-Thames, and the vast underground water reserves that make the Vale's water table unusually high date from that same period.

• 4. Stench, Cholera, and the Great Stink

  ›

  As early as 1357, Edward III put into a royal proclamation that "dung and other filth had accumulated in divers places upon the banks of the river with... fumes and other abominable stenches arising therefrom." Historian Peter Ackroyd recorded that a public lavatory on London Bridge showered its contents directly onto the river below and that latrines were built over all the tributaries feeding into the Thames. In the 19th century things grew catastrophic. Four serious cholera outbreaks killed tens of thousands of people between 1832 and 1865. Gasworks alongside the river leaked spent lime, ammonia, cyanide and carbolic acid into the water. Historians have attributed Prince Albert's death in 1861 to typhoid that spread in the dirty waters beside Windsor Castle. When the flush toilet was widely installed in the 1850s, wells whose water tables mixed with Thames tributaries became contaminated. In the Great Stink of 1858 the pollution was so acute that sittings of the House of Commons had to be abandoned; chlorine-soaked drapes hung in Parliament's windows to block the smell, without success. The crisis forced a solution. Engineer Joseph Bazalgette oversaw the construction of massive sewer systems along both the north and south embankments. Reservoirs and pumping stations were built on the river to the west of London. In the late 1950s, methane discharging from the river's depths caused the water to bubble, and toxins were eating away at boats' propellers. The long-running restoration since the 1950s was formally recognised in 2010, when the Thames won the world's largest environmental prize at the time: the $350,000 International Riverprize, presented at the International Riversymposium in Perth.

• 5. Frost Fairs and Frozen History

  ›

  The completion of the multi-piered medieval London Bridge, under King John, acted as a barricade on the river that slowed the tidal flow upstream and made it far more likely to freeze over in cold winters. In the first recorded Frost Fair, in 1607, a tent city was erected on the frozen river, complete with amusements that included ice bowling. The fairs became extraordinary interludes in London life during severe winters, but they depended on the old bridge's resistance to the current. When a new London Bridge was built in 1825 with fewer piers, the river flowed more freely and the freezing stopped. The last Frost Fair had already taken place in 1814, just before temperatures began to rise again. Other spectacles have punctuated the river's modern story. On the 20th of January 2006, a northern bottlenose whale appeared in the Thames as far upstream as Chelsea; this species is normally found in deep ocean water. Crowds gathered on the banks, but the animal came within yards of the shore, almost beaching, and crashed into an empty boat causing bleeding. About 12 hours later it was reportedly seen near Greenwich, possibly heading back to sea, but a rescue attempt failed and the whale died on a barge. On the 25th of September 2018, a beluga whale was spotted off Gravesend, more than 1,000 miles from its usual Arctic habitat. Nicknamed Benny the Beluga, the male animal was observed over three months throughout the Thames and is believed to have left the river the following January.

• 6. The River as a Sports Ground

  ›

  Over 200 rowing clubs line the banks of the Thames, together accounting for more than 40% of all British Rowing membership. The University Boat Race between Oxford and Cambridge takes place each spring on the Championship Course from Putney to Mortlake. Henley Royal Regatta, held over five days at the start of July, sits alongside Royal Ascot and Wimbledon in the English social calendar. Doggett's Coat and Badge, one of the oldest sporting events in the world, was set up in 1715 by Thomas Doggett, who was so grateful to a waterman for ferrying him home against the tide that he established the race for professional watermen of London. The Royal Canoe Club at Teddington, said to be the oldest canoe club in the world, was founded in 1866. The Thames was used during two Summer Olympic Games: the 1908 Games included rowing on the river, and the 1948 Games included both rowing and canoeing. In 2006, British swimmer and environmental campaigner Lewis Pugh became the first person to swim the full length of the Thames, covering 202 miles from outside Kemble to Southend-on-Sea in 21 days. The official source had stopped flowing because of a severe drought, forcing him to run the opening 26 miles. In 2011, comedian David Walliams swam 140 miles from Lechlade to Westminster Bridge and raised over one million pounds for charity. The Devizes to Westminster International Canoe Race, contested almost every year since 1950, follows the Kennet and Avon Canal before joining the Thames at Reading and finishing at Westminster Bridge.

• 7. Sewage, Plastic, and a Five-Billion-Pound Tunnel

  ›

  In 2013 alone, over 55 tonnes of dilute raw sewage overflowed into the tidal Thames. When London's original sewerage system was designed, storm overflows were expected to discharge once or twice a year; by the time of a 2022 investigation by the Environment Agency, they were happening, on average, once a week. Meanwhile, an estimated 94,000 microplastics pass through some stretches of the river every second, partly from the breakdown of larger objects and partly from glitter and microbeads in cosmetics. One study found that one-fifth of the larger plastic pieces recovered from the river were food packaging. The answer to the sewage crisis was the Thames Tideway Scheme: a tunnel 25 kilometres long running beneath the tidal Thames to intercept overflow before it enters the river, channelling it to Beckton Sewage Treatment Works. The project cost five billion pounds, was delayed by the COVID-19 pandemic, and was completed in February 2025. Modellers estimate it will reduce sewage discharges into the Greater London stretch of the river by 90%. Even so, two million tonnes of sewage are still expected to enter the Thames each year. Mercury pollution, tracked through 60 sediment cores of one metre depth spanning the tidal river between Brentford and the Isle of Grain, shows a clear historical rise and fall, with the highest concentrations found in the central London area between Vauxhall Bridge and Woolwich, where mean total mercury levels reach 2.10 mg/kg, higher than in many other UK and European river estuaries.

• 8. Islands, Salmon, and a Living River

  ›

  The river contains over 80 islands, ranging from the vast estuarial marshlands of the Isle of Sheppey to small tree-covered islets such as Rose Isle in Oxfordshire and Headpile Eyot in Berkshire. Magna Carta Island at Runnymede marks the spot where King John was forced to sign that document in 1215. Platts Eyot at Hampton was where Motor Torpedo Boats were built. Eel Pie Island at Twickenham is remembered as the birthplace of the South East's rhythm and blues music scene. On the 5th of August 1993, the largest non-tidal salmon in recorded records was caught close to Boulters Lock in Maidenhead; the specimen measured 22 inches in length. Salmon had to be reintroduced to the Thames and a succession of fish ladders built into weirs to allow them to travel upstream after industrial pollution had driven them out. Colonies of short-snouted seahorses have been recently discovered in the river alongside tope and starry smooth-hound sharks. Up to 700 grey and harbour seals live in the Thames Estuary and have been sighted as far upriver as Richmond. In August 2022, the opening miles of the river dried up entirely because of the previous month's heatwave, and the source temporarily moved five miles beyond Somerford Keynes. The Thames Tideway Scheme completed in February 2025 projects that two million tonnes of sewage will still enter the river each year, a reminder that the work of restoring one of the world's most storied rivers is still unfinished.