Three Mk V's were converted and sent to Egypt. A Mk IX was converted but went back to landplane later. Unless it was one of the MkV's returned to the UK and later sank then it might not really be a Spitfire. But some other floatplane. On the other hand a number seaplanes and flying boats were deliberately sunk after the war when no longer needed. Sunderlands in Britain and Catalinas in Lough Foyle in Norther Ireland. So who know maybe the spits suffered the same fate.