This was a film about the old Scotland Yard, really – and Jack Hawkins played the Inspector – and there wasn't very much for me to do really, except design the Old Scotland Yard office, and so on, and then I came up with an idea, because I wanted the office of the Chief Inspector to face Westminster Bridge.

But, because we were making it at MGM studios in Borehamwood, or something, and I had a good special effects department, and I said, 'We can build the bridge, and the cars, and buses – the red buses – on a never-ending belt, you see. And when we tried it, it looked pretty good, I must say. And I must say even this very serious American director was fascinated by my bridge, Westminster Bridge, and the traffic going on it.

And so he decided to put Jack Hawkins right into the window, so he got the model bridge, and we started shooting. And then much to my horror, I could see the buses sort of jerking over the bridge and finally coming to a standstill. John said, 'Cut', and without any... 'Ken how long will it take you to fix it?' I said, 'Jack, I don't know, I've got to get the special effects people over and see'. He said, 'If you get it fixed by tomorrow morning there's no problem, because I can shoot around Jack Hawkins, but it's got to work tomorrow morning'.

So I got all the special effects department around and what had happened, which they shouldn't have done, they used a canvas belt, and they... they'd sewn all the cars, and buses to the canvas belt. With the heat of the lighting, the belt stretched and that caused the jerking, and stopping. So they then got a leather belt, and much to our relief, it worked.

And that was really the only sort of encounter which was... I had was with this very frightening American director, but after that we became great friends, and I don't think it was a very good picture, but at least Westminster Bridge worked.