the V-1 guidance system, the Germans needed to know where the V-1s were impacting. Therefore, German intelligence was requested to obtain this impact data from their agents in Britain. However, all German agents in Britain had been turned, and were acting as double agents under British control. On 16 June 1944, British double agent Garbo (Juan Pujol) was requested by his German controllers to give information on the sites and times of V-1 impacts, with similar requests made to the other German agents in Britain, Brutus (Roman Czerniawski) and Tate (Wulf Schmidt). If given this data, the Germans would be able to adjust their aim and correct any shortfall. However, there was no plausible reason why the double agents could not supply accurate data; the impacts would be common knowledge amongst Londoners and very likely reported in the press, which the Germans had ready access to through the neutral nations. In addition, as John Cecil Masterman, chairman of the Twenty Committee, commented, "If, for example, St Paul's Cathedral were hit, it was useless and harmful to report that the bomb had descended upon a cinema in Islington, since the truth would inevitably get through to Germany ..." While the British decided how to react, Pujol played for time. On 18 June it was decided that the double agents would report the damage caused by V-1s fairly accurately and minimise the effect they had on civilian morale. It was also decided that Pujol should avoid giving the times of impacts, and should mostly report on those which occurred in the north west of London, to give the impression to the Germans that they were overshooting the target area. While Pujol downplayed the extent of V-1 damage, trouble came from Ostro, an agent in Lisbon who pretended to have agents reporting from London. He told the Germans that London had been devastated and had been mostly evacuated as a result of enormous casualties. The Germans could not perform aerial reconnaissance of London, and believed his damage reports in preference to Pujol's. They thought that the Allies would make every effort to destroy the V-1 launch sites in France. They also accepted Ostros impact reports. Due to Ultra, however, the Allies read his messages and adjusted for them. A certain number of the V-1s fired had been fitted with radio transmitters, which had clearly demonstrated a tendency for the V-1 to fall short.