A sheet film negative, possibly acetate. The submarine Sealion (1959) undergoing a refit in Admiralty floating dock AFD60 (1966) at Faslane. A close view of the trim pump suction on the starboard side of the hull, taken from the floor of the dock? The Admiralty description for this negative is written as "Trim pump suction stbd" but see negative number N71426 for a different description for the large oval grating. An Admiralty copy negative of a whole plate photographic print.