A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the auxiliary machinery space between 62 and 68 stations below the main flat looking aft and down on the starboard side at 63-64 stations showing an unit marked 7½" fan DB C3B F8, partly obscured by a steel ladder which leads up to the control room. On the left is an 880v electric motor. A vertical format negative.