I don't know if it needs to be a round hole, I just assumed that it had to be a whole hole. (No pun intended.)
I'm just a militaria collector and enthusiast so only know what dealers say and what's online.
My personal opinion is that there is a chance that the law may change so that some of the later U.K. spec deacs may be permitted to change hands where the spec is very close to the current E.U. spec.. Nothing more than a hunch.