The changes at Bletchley Park make this cover very collectable indeed as these scenes will never be repeated.
The Royal Mail 'Trooping the Colour' stamps have been cancelled on their first day of issue with a facsimile of the secret label badge worn by the code breakers of Bletchley Park. The badge also features in the top centre of the cover.
The cover features a parade by the 'Ox and Bucks' in 1940's uniform. They are famous for their 'Pegasus Bridge' exploits ahead of the D-day landings.