A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the generator room between 77 and 92 stations looking aft, to starboard and up from the centreline of the main flat at 86 station showing the temperature gauge fitted to number eight cylinder in the right hand bank of the starboard 16 cylinder Admiralty Standard Range diesel engine. The air intake pipe is prominent. An automatic emergency lantern is mounted under the deckhead. A vertical format negative.