This FDC has been signed by David Balme who retrieved the Enigma machine from the sticken U 110 and the U Boat's Enigma machine operator. The story ws the basis of the highly fictionalised film U 571. At the time of issue they sold for £380. Probably priceless now.
Stamps are Royal Mail 'Submarines' issued. The original unsigned version sold out in less than 3 weeks.