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 main flat at 80 station showing the upper part of the starboard 16 cylinder Admiralty Standard Range diesel engine including the instrument panel at the forward end. Above the instrument panel is a box labelled 'Ind. hull valve & stop snorting telegraph rec.'. All of the cylinders of the engine are fitted with temperature gauges.