Look like an FN FAL, probably produced under contract by the british gov and given the designation. If I remember they were used by both sides in the Falklands war the british where armed with the semi auto L1A1 and the Argentinians were armed with the full auto/ semi auto FALs. Other then that I'm sure someone else will come along with more info.
"come on you sons of b***hs! do you want to live forever?" Sergeant Daniel Daly, USMC, Belleau Wood France June 6th 1918
"You can be as mad as a mad dog at the way things went. You could swear, curse the fates, but when it comes to the end, you have to let go" Benjamin Button