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 to port and down below the main flat from the main flat at 91 station showing the port air start pump starter unit against the aft bulkhead at 92 station on the left. It is above the air start cylinder below the flat. A large handwheel is marked 'PP Suctn.' and an hydraulic valve unit is marked 'Aft services inlet port'. A vertical format negative.