That would make sence Peter as I have some RAF training notes from RAF Cosford from the 1980s and it mentions the L4A1 aswell as the L4A4 so assume that the A1 (A6) and A4 were in service together. Lets face it, the RAF wouldn't really need an LMG (Except RAF Reg) so why give us the up to date kit. I remember when I joined in 1995 that there were still L1A1 parts knocking around (Sadly no rifles) and I remember clearing out some scrap from the armoury at Cosford and in amongst it were brand new L4 breech blocks, newly coppered L59 bolts and loads of L2 parts.