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 immediately abaft the bridge wing looking aft and to starboard at the Knebworth-Corvus 3 inch rocket launcher platform between 33 and 36 stations on the starboard side of 01 deck. the launcher has a canvas cover. Fitted to the forward side of the platform is the launcher operator's position with a maintenace switch, a winterisation switch, a fire warning rattler, a loudspeaker, a telephone handset and a load/safety change over switch. A vertical format negative.