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 centreline of the main flat at 88 station showing the air intake pipe at the aft end of the starboard 16 cylinder Admiralty Standard Range diesel engine. A Budenberg pressure gauge is above the pipe. The ladder to the escape hatch is rigged on the right and a Paragon No. 5 semi rotary pump is against the aft bulkhead at 92 station.