Colin Firth got it right! I was talking about the blue-red-blue Guards ribbon badge backing now worn by all Guardsmen on their berets. The exception was (and still is) the Scots Guards officer’s tartan backing, which was indeed worn by their officers in the Falklands War, but not by the Scots Guards Other Ranks.
Thanks, every day's a school day - though now I think about it I must have seen them around...