At the end of October 1940, while the British and German air forces were nightly striking at each other's cities, Captain Norman Macmillan (a decorated RFC veteran and former head of the National League of Airmen) argued in Flight that Britain's greatest need was for the development of a bomber which was possessed great speed (400 mph), long range (5000 miles) and high bombload (5 tons), for
We may dominate the seas, but that to-day is not enough. We must dominate the land as well, and we do not do so. We shall not be able to dominate the land until we possess bombers which can reach out to the uttermost corners of the earth, from the bases we possess. And we cannot win this war until we are able to straddle the whole of Europe from the air.
That means range and speed.1
One man answered the challenge: Noel Pemberton-Billing, founder of Supermarine and sometime demagogic independent MP. He rejected the contemporary dogma of the self-defending flying fortress, which had proven a failure in daylight operations and so were forced to bomb less accurately at night. The only defence, he believed, was speed, not guns. His design -- the P.B.49, a twin-engine monoplane with a crew of three -- more than met Macmillan's specifications, and had the added virtues of being small and inexpensive.2 In fact, it was around the same size as the later Mosquito, and about as fast; but had more than twice the bombload at its maximum combat range of 8000 miles, itself more than five times the range of the wooden wonder. At shorter ranges, more bombs could be carried -- 10 tons per bomber to Berlin, for example. How was this incredible performance to be achieved? By slip-wing, of course.