BEagle,
Whilst I agree with you, the issue of medals applies whether you wear them while serving or not as I am sure you know. However:
Prince Charles asked one veteran who was wearing a maroon ribbon and a hammer and sickle impress whether he had been awarded this for Russian convoys or some such. This was before the Russians awarded a convoy medal and it also looked more like a British medal.
"No Sir," he said. "I got it from Tito . . . for service in Yugoslavia."
PS,
I seem to remember that the ban on foreign medals applies if there is a British medal for the same campaign.
PPS,
The Croix de Guerre seems to be an exception.
Also, in the cabinet war rooms Churchill's medal collection seems extremely eclectic.