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 forward, to port and up from the main flat at 82 station showing the top of the main control console between 80 and 81 stations. High pressure air compressor starter No. 2 is against the port side of the boat with a hull valve next to it.