hand the magnetron to the Germans. Years later, Lovell attempted to discover the reasons for this negative report, but he found that no one recalled Rabi being so negative. The only explanation that anyone had was that problems getting the sets working were taken out of context. Taffy Bowen had noted that he had significant trouble getting the sets to do anything in the US; in testing against Springfield, Hartford and Boston, the display simply did not show anything. By September, a prototype version suitable for operational use was ready. In spite of all the concerns, on 15 September Churchill personally released the magnetron for use by Bomber Command. While the debate raged, it had been noticed that German submarines had been fitted with a new radar detector, later known to be the FuMB 1 Metox 600A, which allowed them to detect Coastal Command's ASV sets operating on the older 1.5 m band. In September the decision was made to prioritize construction for the ASV Mk. III. It was felt the chance that a magnetron falling into German hands from a patrol aircraft was vanishingly small. Emergency relocation The Air Ministry radar groups had originally formed up at Bawdsey Manor on the eastern coast of England. When the war began in 1939, this location was considered too exposed to a potential German attack, and a pre-arranged move to the University of Dundee was carried out almost overnight. On arrival, it was found nothing was prepared and there was little room for the teams to work in. Worse, the team working on airborne radars ended up at a tiny private airstrip in Perth, Scotland that was entirely unsuitable for development. It took some time before the nature of the problem was finally accepted by management and a search began for a new location. In late 1939, the Airborne team moved to RAF St Athan, about from Cardiff. Although this location should have been ideal, they found themselves in a disused hangar with no heating, and work became almost impossible as the weather turned cold. The main research teams remained in Dundee during this period. The ongoing search for a more suitable location for all the teams led to the selection of Swanage on the southern coast of the UK. The rest of the original radar group moved there in May 1940, the AI group arriving the day before them. The AI