It's PK664, a Mark 22, which has never been displayed at Hendon (they already have a 24,) and which was loaned to the Science Museum, recently, displayed in a "disassembled" state, so it's possible that it still hasn't been put back together.
It was sold back to Vickers, and there are unconfirmed reports that it was fitted with a Griffon 85 contraprops (not on it, now,) possibly as a test-bed for the Seafire 47.
In the last issue of "Wrecks and Relics," 66 "Spitfire Seafires" are listed as being extant in the U.K; some might only be partial, and some might be fibre-glass replicas, but they're not exactly in short supply, and we're told that the recently-discovered Mk.IX, used in the "Battle of Britain" film, is on its way back here, from the U.S., for restoration to fly.
Egypt took delivery of several Mk.22 Spitfires, post-war, and used them against Israel; as their only other "Spitfire" is a wreck, the reason for their interest in acquiring another is obvious.