In the 1870s London’s riverside roads were gridlocked, with horses and carts and even pedestrians queuing for hours to cross. Another bridge to the east was desperately needed. But this section of the River Thames was the busiest port in the entire British Empire.

The City of London’s architect Horace Jones designed a bascule bridge, with arms that could be raised to let ships through. The hydraulic lifting mechanism was a tremendous success. The bridge could open fully in just five minutes.

When Jones died in 1887 before construction began, Sir John Wolfe Barry took over the project and a whole galaxy of engineering superstars worked on its construction – Arrol, Armstrong, and Brunel’s son Henry Marc.

It cost £1m, and it came in on budget - most unusual for a bridge.