A sheet film negative, possibly acetate. The submarine Sealion (1959) undergoing a refit in Admiralty floating dock AFD60 (1966) at Faslane. A port bow view, taken from the floor of the dock fine off the bow looking aft and slightly to starboard. Her port anchor has been lowered to the dock floor and is leaning against the keel blocks. An Admiralty copy negative of a whole plate photographic print. A vertical format negative.