At the beginning of the 19th century, London was one of the busiest river ports in the world, and the 600-year old stone bridge over Thames was long out of capacity. Like many medieval bridges, this too was crammed with buildings, some of which overhung the road creating a dark tunnel through traffic passed. Although the bridge was some 8 meters wide, only half of it was available for traffic. This roadway was shared by ox-carts, wagons, coaches and pedestrians coming from both directions. At peak hours, a crossing could take up to an hour.

It was clear that another crossing was needed, but this new crossing was not to be a bridge but a tunnel under the River.