115 Sqn - The squadron came back on 21 August 1958, when No 116 Squadron at Tangmere was renumbered. It was now a Radar Calibration unit operating Varsities and Valettas.
and
On 21 August 1958 No. 116 Squadron at Watton was re-numbered No.115 Squadron. The squadron now had a completely different role. It was part of No. 90 Signals Group and its task was somewhat prosaic but vital, that of calibrating from the air all radio and radar installations at RAF airfields. Later in the year it moved to Tangmere, where it remained for five years on this task and also took part in calibrating ships' installations. It also flew a few Vickers Valettas for a year or two.
Note the latter extract does not mention the Varsity. Of course radar calibration can hide a multitude of things including plotting the ground emitter and recording its parameter.