Looking at the above -
RDF - restrike - 100% certain. (If it is "Gaunt . London" that is).
9th Lcrs - possible restrike, not sure. I have a 17/21 Lcrs which is exactly as your 9 Lcrs (except for the regt of course) and I can't decide about that either. Maybe they are both fakes or just made around the same time. It's better quality than most of the restrikes.
Incidentally, I have a 27th Lcrs, complete lettering, no tint on back (unless Roger has polished it off
) but still 100% fake!
The Cavalry restrikes which turn up most frequently are - 3rd Carabineers, 27th Lancers & 24th Lancers, probably in that order; in my experience anyway.
David
PS... only large size buttons were restruck. The "Gaunt London" backmark appeared much earlier on some small size buttons (such as your West Yorks above), probably simply because of space limitations.