Pete,
Thanks for posting the link to the Commercial Navy, very interesting to see those markings.
Here are the barrel proofs on a Vickers.
At least there is no question of their belonging on this gun!
Regarding the original question in this thread, in my opinion, British proofs are an interesting part of the story of a Luger which they are on. Given two identical pistols however, one of which has British proofs and the other which does not, the British proofed gun is devalued compared to the other.
I think this comes from there being no official or contract British acceptance of the Luger. British proofs are on these guns by an arbitrary legislative act, not as part of an an official, organized procurement system. They are not dissimilar from U.S. import marks in this respect.
--Dwight