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 and down from the starboard side of the main flat at 81 station showing the lower part of the 16 cylinder Admiralty Standard Range diesel engine on the right. Various panels, gauges and valves are against the boat's side. A vertical format negative.