In February 1943 it was renamed RAF St. Mawgan[7] and in June 1943, the United States Army Air Forces took over and carried out a number of major improvements, including a new control tower and a further extension of the main runway.

[8] In 1951, it reopened as an RAF Coastal Command air base for the Air-Sea Warfare Development Unit RAF (ASWDU) where trials of new electronic equipment were carried out, to ascertain the suitability of the equipment for general use in Coastal Command, and for maritime reconnaissance, flying mainly Avro Shackleton aircraft, with support from a few Avro Lancaster aircraft.

[11] 7 Sqn, flying English Electric Canberras, operated at RAF St Mawgan as target tugs from 1970 until 1982, with 22 Squadron moving out in 1974.

[13] The Joint Maritime Facility (JMF) (50°26′17.0″N 5°00′22.7″W / 50.438056°N 5.006306°W / 50.438056; -5.006306) at St Mawgan was commissioned 18 August 1995 after equipment from United States Naval Facility, Brawdy, Wales, a Sound Surveillance System (SOSUS) shore terminal commissioned 5 April 1974, had been transferred and the sea systems had been remoted to the new JMF.

It was announced in early 2009 that the JMF would close in order to save the US Navy £6.5 million per year, losing 22 jobs in the process.

[17][18] RAF St Mawgan was the last remaining US Navy installation in the U.K.[19] The systems at the JMF were remoted to the Naval Ocean Processing Facility (NOPF), Dam Neck, Virginia with the remaining personnel from JMF at RAF St Mawgan moved to the Virginia facility.

Until May 2008, RAF St Mawgan was primarily used as a Search and Rescue training camp and was home to 203(R) Squadron, equipped with Sea King helicopters.

[25] On 1 December 2008 the airfield part of the camp (including the civilian side) closed but the RAF still remain on a reduced area.

This was to allow full control of the airport to be handed to Cornwall County Council, with work including a new ATC tower and runway lights.

[28] In March 2015 the former airfield of the base became a strong contender to be the first UK spaceport for horizontal take off and landing after being shortlisted by the government.

[50] The Royal Air Force maintains a small workshop on the station, enabling construction of components for the upgrading of aircraft for all three services.