I presume you are refering to proof marks, and not the ones S&W makes at the factory on All model 10 revolvers.
Anyway, Smith & Wesson has exported thousands of revolvers to Europe. When they arrive the receiving country usually requires they be proofed in a government proof house. In a few cases certain countries would accept German proof in place of their own. So all revolvers arriving in Europe or England would be proofed and marked by somebody.
Model 10 revolvers were also used by some police and security forces. These may have government ownership markings in addition to proof marks. So far as I know European military forces have not used revolvers in recent years, but there could be some special unit exceptions.