+1. Emphasis mine above. There are numerous examples of what appear to be simple production restarts or reverse-engineering projects that become horribly mired and produce nothing very useful at all.
Nowadays there are capable British firearm designers / manufacturers, and there are large-scale firearm designers / manufacturers, but there are NO large-scale British firearm designers / manufacturers. When a full replacement for the L85 is decided upon, it won't be a UK designed and manufactured weapon, unless someone decides to create a new company and build all the infrastructure to do it!
Not sure what you call 'large scale' but this company seems to get by:http://www.manroy.com/
In the States, lots
of companies that never produced a gun before made weapons*. This lasted well into the postwar period. International Harvester had made M1 Garands in the Korean War period, not having made them in WW2. Some of the best M14s for example were made by TRW which hand not made rifles before. OTOH Harrington and Richardson, a manufaturer of guns of long standing, had serious QC problems. IIRC General motors made M16s in the Vietnam era. There are lots of small companies turning out semi and full automatic centrefire rifles in the states, often starting off in a shed with a few lathes and graduating to CNC machines. Given the will, this is not a hard capability to reinstate.
*For example, for the M1 carbine alone:
* Inland Division, General Motors (production: 2,632,097), sole producer of the M1A1 Carbine. Receiver marked "INLAND DIV."
* Winchester Repeating Arms (production: 828,059) Receiver marked "WINCHESTER"
* Irwin-Pedersen (operated by Saginaw Steering Gear and production included with Saginaw total)
* Saginaw Steering Gear Division General Motors (production: 517,213 ) Receivers marked "SAGINAW S.G." (370,490) and "IRWIN-PEDERSEN" (146,723 )
* Underwood Elliot Fisher (production: 545,616) Receiver marked "UNDERWOOD"
* National Postal Meter (production: 413,017) Receiver marked "NATIONAL POSTAL METER"
* Quality Hardware Manufacturing Corp. (production: 359,666) Receiver marked "QUALITY H.M.C."
* International Business Machines (production: 346,500) Receiver marked "I.B.M. CORP."
* Standard Products (production: 247,100) Receiver marked "STD. PRO."
* Rock-Ola Manufacturing Corporation (production: 228,500) Receiver Marked "ROCK-OLA" 
* Commercial Controls Corporation (production: 239) Receiver marked "COMMERCIAL CONTROLS"
Edited by Chris Werb, 01 December 2010 - 1923 PM.