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 up from the main flat at 81 station showing pipework, cabling and electrical boxes against the boat's side. The port 16 cylinder Admiralty Standard Range diesel engine is on the left and temperature gauges are fitted to each of the eight cylinders in the right bank.