The L85A1 (part of the SA80 small arms family) was adopted by the British military in 1985 as a new generation of small arms to replace the L1A1 FAL (one quick note, where "A1" indicates a revision in American designations, it is simply the first iteration in British ones - there was no "L85"). As a bullpup rifle, the L85A1 was intended to replace both the FAL and Sterling SMG, similar to the French replacing the MAS 49/56 and MAT 49 with the FAMAS.
Unfortunately, the L85A1 had massive problems of both reliability and durability. They were kept pretty much hidden until Desert Storm, when it became unavoidably clear that the weapon was seriously flawed. The UK government denied the problems for several years, until finally contracting with H&K (then owned by Royal Ordnance) to redesign and rebuild the rifles. The result, after changes to virtually every part of the rifle, was the L85A2 - a much better rifle that will be tainted with its predecessor's reputation regardless.
Mechanically, the L85A1 and A2 are basically copies of the Armalite AR-180, with a multi-lug rotating bolt and a short stroke gas piston. It feeds from STANAG magazines, and it universally fitted with the heavy but rugged SUSAT optical sight.
Thanks to the Institute of Military Technology for allowing me to have access to this rifle (which is extremely rare in the US) and bring it to you! Check them out at: