I'd like to start by talking about my collaboration with David Marks and Julia Barfield who I first met probably about seventeen years ago when Julia was working for Foster's and we were both working on the BBC Radio headquarters building; and at the same time we did a competition for the Grand Buildings at Trafalgar Square with David and another architect, Marcus Lee; and it was the start of a long conversation that we had about buildings and the built environment and derivation of form.

When I was in Los Angeles a few years later they asked me if I'd like to collaborate with them for a competition for a bridge. It was a competition launched by the Institution of Civil Engineers that was called "An Image of a Bridge of the Future". And we had this idea of a bridge that you could experience as you went across it, rather like the primitive suspension bridges where, when you walk across the gorge, they move around as you go. And Julia found this reference in Darcy Thompson's "On Growth and Form" about the animals, the quadrupedal bridge spanning between his front and back legs, and the bones carrying compression and the tendons modulate your movements as you lean forwards and backwards and the loads change, so the structure is dynamic and yet strong. So our idea for the bridge was to have a series of kind of vertebrae which would go from one side to the other. And on one side we'd anchor it so it would be rigidly fixed both vertically and horizontally and have a series of vertebrae which would be connected with tendons and it would be slightly arch-shaped and at the other end be supported just vertically by the ground. So, as you walked along it, that end that's only supported vertically would slide in and out. It would be just for pedestrians so it didn't matter if it moved, and that would put the people on a travelator. And we thought, because I was in Los Angeles at the time, and they were in Britain, that we'd put it over the Grand Canyon. And they did a very beautiful poster of it. We were lucky we won the competition.