A roll film negative. On board the submarine Sealion (1959) towards the end of a long refit at Portsmouth. The photographer is in the motor room between 92 and 103 stations below the main flat looking to port from the centreline at 102 station showing the aft end of the port main motor on the right. A vertical steel ladder leading up to main flat is in the foreground. Valves are against the aft bulkhead at 103 station on the left, including a shuttle valve and an hydraulic tensioning pulley control valve. A speed control box is beyond the ladder in the upper left. A vertical format negative.