It's an interesting thing Civilian proof law, I think I am right in say that it is a legal requirement for all firearms sold in the UK to be within proof (Britishor CIP), I guess if a rifle is surplussed and sold for export however, its not required.
Its amazing though (and I am sure the RFD's and collectors on here will agree) the amount of Milsurp firearms that are sold out of proof in the UK, even worse, the RFD's who haven't got the first clue about proof and the law and think military proof/ownership markings are good enough!
The lack of knowledge on occasion is simply breathtaking!