were carried on board aircraft carriers, the Swordfish being flown from the smaller escort carriers where they formed a valuable anti-submarine presence when used over the numerous North Atlantic convoys. The Oboe blind bombing system was designed and developed by Frank Jones at TRE in collaboration with Alec Reeves at the Royal Aircraft Establishment. Oboe transponders were fitted to Mosquitoes of 109 Squadron, which developed the use of the device as part of the Pathfinder Force. The Mosquito was chosen because the transponder device mounted in the airplane was not large, and its use required the aircraft to fly for 10 minutes on a straight and level course. That being the case speed was essential to avoid being intercepted. In addition, the Mosquito could reach 30,000 feet altitude, and this improved the range across the continent that the device could be used over. The H2S radar used the newly developed cavity magnetron. It was carried by RAF bombers to identify ground targets for night and all-weather bombing. Initial trials were with a Handley Page Halifax and despite setbacks the equipment later became a standard fitting on Halifaxes, Short Stirlings and Avro Lancasters. It was also fitted to the post-war Vickers Valiant, Avro Vulcan, Handley Page Victor, and bomber versions of the English Electric Canberra. H2S in its final form of H2S Mk 9 was still being used on Vulcans as late as the 1982 Falklands War. C. E. Wynn-Williams worked on these navigational radars, but was transferred to cryptographic work at Bletchley Park. The Automatic Gun-Laying Turret (AGLT) was an airborne radar used in bombers by the gunners against attack by fighter planes. It was designed by Philip Dee and developed by Alan Hodgkin. The device allowed a turret gunner to fire at and hit a target without ever needing to see it. Known by the codename 'Village Inn', the AGLT was installed in a number of Lancasters and Halifaxes and used operationally during the war, and was also fitted on some post-war Avro Lincolns. Radar trainers were designed and developed by Geoffrey Dummer. The priority that Winston Churchill placed on the development and deployment of radar is described by Sir Bernard Lovell: Every day Sir Robert Renwick would phone Lovell or Dee, asking "any news, any problems" [and these would be] dealt with by Renwick's immediate access to Churchill. Other work Radar jamming was developed by Robert Cockburn. The