At the end of hostilities, there was no longer a role for Martlesham Heath as an operational RAF airfield and no prospect of the A&AEE returning, but the site was again used for a number of experiments with planes and armaments. However, its use declined in the 1950s, and the airfield was closed in the early 1960s.
Various proposals were put forward for the development of the site, including the proposal that it should become a civil airport. Parts of the old airfield were let out to light industry and storage companies. In 1963 the lease of the site was sold by the Air Ministry to Bradford Property Trust Ltd, for a price of £72,500.
In 1968, the Post Office purchased part of the airfield and surrounding farmland and announced that they would be relocating their Research Department from Dollis Hill to a new centre to be built at Martlesham Heath. The building work took place in the early 1970s and this site has remained as the central research and development facility through the changes that have taken place with the separation of British Telecom from the Post Office and the privatisation of British Telecommunications. In the 1980s, the facility was renamed as BT Labs and was subsequently developed into a high tech business park called Adastral Park in the 1990s.