Hi Richard, the scope mounting plate suggests it is a later model from the late 1960s (earlier Falcons had no scope plates fitted). These scope rail plates -- as with the scope rail plates which started to appear on Webley MkIIIs around this time -- are not traditional mount grooves as we know today, but are basically shaped steel plates spot welded on to the action, and given time, if used to clamp a scope to, will shake loose and detach (fall off) so would strongly recommend not using them. An entire new sight assembly shouldn't cost you much more than £20 however, which after paying out to have all the other work is a small price to pay to have a complete mechanically sound bit of working Webley kit
ATB & HTH:
Gareth W-B.