With the closure of the post office and all the changes at Bletchley Park this cover has even greater significance.
First day of issue cancel for the Royal Mail 2006 Christmas stamp issue says "Merry Xmas" in Enigma code. There is also a matching Christmas card inside the cover.
First day cover Features scenes from Bletchley Park that will no longer be seen in this way.
What a super piece to go with other BPPO Christmas issues as some unique art and history.