IMHO this Rigby .404 is a typical example from the Paul Roberts 1984-1997 period. The 2 numbers under the "LP" will certainly date it, as they are the year of proof, 1985? Here are 5 pics from Rigby's advertizing from that time. As you see, they show most of the "non-Rigby" features you criticize: The close pistol grip, the spearpoint or quarterrib sight base, the front sight with protector. BTW, at that time they built most of their .416 and .450 Rigby rifles on modified Brno ZKK actions, the only true magnum length actions available in the 1980s.