Photographed on the 26 Aug 1983 at Portsmouth the frigate HMS Londonderry.
Grateful to Stevo for leading me to the following information
The 1978 refit of HMS Londonderry saw some considerable changes to this Rothesay class anti submarine frigate. She was fitted out as a trials ship for ASWE.
A third mast was fitted to carry the TYPE 1030 STIR radar, the gun was removed, a new propulsion system was fitted to check the quietness of waterjets and a CAAIS system was fitted to improve the ability to handle the amount of information being generated.
Follow the link for interesting action of life refitting naval vessels