It ushered in Electronic countermeasures (ECM) warfare, jamming enemy radar installations from October 1942 as the only such squadron in the RAF initially.

As part of 11 Group, 515 Sqn performed radar jamming duties, using Moonshine and Mandrel equipment.

At the time of its disbandment on 10 June 1945, 515 squadron had carried out 1,366 operational sorties with the Mosquito with a loss of 21 aircraft, with most of its aircrew transferring to No.

515 Squadron RAF to defeat Freya radar and was developed at the Telecommunications Research Establishment (TRE).

Mandrel was the code-name for a jammer deployed against Freya and Würzburg radars used by aircraft of 515 sqn and 100 Group.