Hidden London: The Thames Tunnel

In medieval Europe, river crossings were prized real estate. The original London Bridge was a fine example, with more than 90 shops, houses and chapels crammed along its 275-metre span. Even today, in Florence, you can stroll across the Ponte Vecchio and be tempted by the jewellers that line the Arno. Yet one of London’s busiest thoroughfares on the Thames is not a bridge at all, but a shopping arcade twenty metres below the river. The Thames Tunnel, once hailed as the Eighth Wonder of the World, opened in 1843. It was the first underwater passenger tunnel and drew over a million visitors in its opening 10 weeks, making it the world’s most popular attraction at the time. No self-respecting visitor to London left without descending into its depths or buying a trinket marked A Present from the Thames Tunnel.

So how did London acquire its underwater Victorian mall? For centuries, crossing the Thames was a challenge: until the 1700s London Bridge was the only fixed crossing, and by the early 1800s only four more had been added. Meanwhile, pressure grew to link the eastern docklands on either bank. An early attempt using Cornish miners failed: their skill with hard rock was useless against the quicksands beneath the river. Enter Marc Brunel, an ingenious French engineer who had recently tried, unsuccessfully, to persuade the Czar of Russia to build a tunnel under the Neva. In London he drew up plans for a 400-metre tunnel from Rotherhithe to Wapping.

Marc Brunel was a remarkable figure. Born in Normandy, he served as a Royalist officer in the French Navy before fleeing the Revolution to the newly formed United States, where he became chief engineer of New York City. In France, he had met Sophia Kingdom, an Englishwoman who, after his escape, was imprisoned during the Terror. When he finally reached England they married and had three children: two daughters and a son. More of him later.

Brunel’s plans for a tunnel under the Thames were approved by Parliament, and with backers including the Twining tea family and the Duke of Wellington, he began work in 1825 using his co-invention, the tunnelling shield — a giant iron frame divided into 36 compartments. Each workman dug a small section of earth protected by movable boards; then the whole shield was inched forward by screw jacks while bricklayers lined the tunnel behind, advancing safely under the river step by step. The main shaft was equally ingenious: a massive iron ring with a 12-metre brick wall above it, forming a 15-metre-wide ‘cookie-cutter’ that sank under its own weight as the team dug below.