On board the Type 12 general purpose frigate Plymouth (1959) alongside the south side of number 3 basin in Chatham Dockyard at the end of a modernization which commenced in August 1966. The ship is berthed starboard side to the quay. The photographer is in the sonar control room between 35 and 39 stations on the starboard side of 1 deck looking forward showing three sonar control positions identified by the photographer as the "C.O.2 panel". Above the panel are dimmer switches, a firing pistol, a remote plug box for A/S type 1070B and an A/S type 170B servicing line.