There were quite a few civilian-made L1A1 scope top covers back in the days when the rifles were legal to own in UKicon, but IIRC all of them had brazed-on rails of one type or another. Its interesting that shilly's topcover is spot-welded, which makes it look quite "factory" in appearance, particularly as the suncorite has the "look" as well. However it doesn't match any of the 50-odd experimental and factory top covers listed in the histories of the FAL rifle. Would be interesting to see it close up.

This is a typical civvie mount, although - ironically - this particular specimen was actually procured as a "local purchase" for military use.