On board the Type 12 frigate Lowestoft (1960) in No. 3 basin at Chatham Dockyard near the end of her modernisation which commenced 15 March 1968 and finished 31 May 1970. She was in the basin throughout May 1970. The photographer is in the H.O. 20 sonar compartment between 15½ and 19 stations on 4 deck looking forward and slightly to port showing the waterline markings on the forward bulkhead. The H.O. (hull outfit) 20 sonar compartment contained the Type 177M sonar. A vertical format negative.