I am assuming by the buttstock pressings. That these guns in the film, are L2A2's, & NOT the later L2A3's the final production design?

These buttstocks, with their distinctive side bar pressing ribs. will NOT fit any L2A3 versions. This is because the position of the Trunion on the receiver, is further back than the later L2A3 variants. Sterling's claim that 'All' parts in current production (L2A3) will fit any of the earlier marks of gun'. Was not QUITE correct in that sense!.....

There were indeed MINOR differences between the L2A3 & L2A4. But these were of no real consequence, and true enough on Sterlings claim there. That all parts were fully interchangeable. The obvious differences were: Foresight Protector shape, Trigger Profile, Rear sight has a 'wing' on the outside of it's protector. To change the sight position. This was eliminated on the 2A3 & changed with finger & thumb movement. But you could if you wanted to, swap them over. The same went for the trigger group, as a complete unit. ALL marks of breech Bolt were fully interchangeable, if needed/wanted to. to get you out of trouble anywhere in the world. To keep the weapon 'Running' in emergency conditions......A truly remarkable design, & one of my Favourate SMG class of weapon to fire!