But the footbridge idea remained. Hawkshaw’s bridge was designed with two narrow walkways slung off either side. Later, the railway was widened and the upstream walkway was lost. That’s the way things stayed right through the twentieth century, with a single narrow, congested and frightening snicket of a walkway, right next to the rumbling and screeching trains, forming the only direct connection to the South Bank. Muggings and murders happened there. For the Festival of Britain of 1951 on the South Bank, a wide but temporary Bailey Bridge was added and it was confidently predicted that a permanent solution would very soon be found. But typically of Britain and its problems with basic infrastructure, it wasn’t.

Even when the moment finally came in the mid 1990s, when the previously bickering riverside boroughs formed themselves into the Cross-River Partnership, a serious architectural competition was held and the Millennium Commission stumped up half the cash, it was still a saga. At first Westminster, the borough charged with building and part-funding the bridge, tried to remove the architects from the project and had to be given a caution by the design police. But that was nothing compared to the bomb scare. Foundations for the twin bridges were already being built when London Underground - which has two tube tunnels crossing the Thames very close by - brought the project to a halt by saying that wartime bombs in the river with time-delay fuses could be triggered by the piling work and so flood most of the tube network, with catastrophic consequences. Nobody thought this was terribly likely, but nobody was prepared to take the risk either.