In any case, that terrible Battle of Stalingrad in January 1943, when von Paulus – I think it was eighth army – was completely destroyed. Bomber Command received permission to use the equipment operationally over Germany and I had an agreed code from O'Kane who phoned me one Saturday morning and said, 'It will be a nice weekend to come into the country'. So I drove over to Whitten and on that Saturday, the last... January 30th, the last weekend in January 1943. The bomber force took off to attack Hamburg. Now, that was good fortune from our point of view. I believe I was told that the original idea was to bomb Berlin on that night.

Now, for reasons which will appear later, Berlin would have been a very poor target. Hamburg, on the contrary, was a very good target because although our equipment was far from being good, it was at least extremely good on coastlines and showing up the difference between water and land. Well, that night at Whitten... you know, even 60 years later it's just unforgettable. The pathfinders, the whole... two squadrons took off, and sometime in the early hours they began to return. Bad weather had turned them back or engine failure or apparatus failure. Then at last one navigator came in and put his thumb up. He said, 'Marvellous'. He said, 'The docks on the Elbe stood out on the screen like my fingers', you know. That was our good fortune. So that was the first attack on Berlin and then that was the beginning of the operations with H2S.