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 down from the main flat at 80 station showing the lower part of the starboard 16 cylinder Admiralty Standard Range diesel engine including the bottom of the instrument panel at the forward end. Under the instrument panel is a revolution counter and an overspeed tachograph unit as well as numerous taps and valves. All of the cylinders of the engine are fitted with temperature gauges.