While we wait for the knowledgeable to pitch in, I have seen a couple of rifles marked with a discreet FTR on the TMH, but these were service reworked (in house, or contractor, I don't know), this would have been carried out and so marked, in the 1970's I would assume?

But I don't think rifles refurbished for war reserve were marked with FTR in the late 1980's or early 1990's... Never seen one anyway.

Refurbished at considerable cost by Parker Hale .... Then sold for peanuts!