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 port bow taken from the side of the dock looking to starboard and aft showing the asdic dome covering the sonar type 187 transducer, the open shutter to number two torpedo tube and the anchor. Scaffolding which obscures the lower part of the hull has been erected. An Admiralty copy negative of a whole plate photographic print.