force. An alternative solution was urgently needed and, in 1934, the Air Ministry set up a committee, the CSSAD (Committee for the Scientific Survey of Air Defence), chaired by Sir Henry Tizard to find ways to improve air defence in the UK. Rumours that Nazi Germany had developed a "death ray" that was capable of destroying towns, cities and people using radio waves, were given attention in January 1935 by Harry Wimperis, Director of Scientific Research at the Air Ministry. He asked Watson-Watt about the possibility of building their version of a death-ray, specifically to be used against aircraft. Watson-Watt quickly returned a calculation carried out by his young colleague, Arnold Wilkins, showing that such a device was impossible to construct and fears of a Nazi version soon vanished. He also mentioned in the same report a suggestion that was originally made to him by Wilkins, who had recently heard of aircraft disturbing shortwave communications, that radio waves might be capable of detecting aircraft, "Meanwhile, attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required". Wilkins's idea, checked by Watt, was promptly presented by Tizard to the CSSAD on 28 January 1935. Aircraft detection and location On 12 February 1935, Watson-Watt sent the secret memo of the proposed system to the Air Ministry, Detection and location of aircraft by radio methods. Although not as exciting as a death-ray, the concept clearly had potential, but the Air Ministry, before giving funding, asked for a demonstration proving that radio waves could be reflected by an aircraft. This was ready by 26 February and consisted of two receiving antennae located about away from one of the BBC's shortwave broadcast stations at Daventry. The two antennae were phased such that signals travelling directly from the station cancelled themselves out, but signals arriving from other angles were admitted, thereby deflecting the trace on a CRT indicator (passive radar). Such was the secrecy of this test that only three people witnessed it: Watson-Watt, his colleague Arnold Wilkins, and a single member of the committee, A. P. Rowe. The demonstration was a success: on several occasions, the receiver showed a clear return signal from a Handley Page Heyford bomber flown around the site. Prime Minister Stanley Baldwin was kept quietly informed of radar progress. On