A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the control room between 59 and 69 stations looking forward, to starboard and up from 61 station showing the Mark 17 T.C.C. unit manufactured by Laurence Scott & Electromotors on the left with the Mark 1 torpedo order firing unit next to it. A sonar type 187 bearing repeater is under the deckhead on the forward bulkhead. A vertical format negative.