Ok - a bit of self-help has done wonders. I have tracked down a copy of the
RAF Handbook of the Vickers Gun, May 1919. I found it in the (Australian) Defence Library Service catalogue.
It has fantastic pictures of the gun and associated parts. The pictures of cutaway and multiple-views of parts should make the job of making a replica gun a whole lot easier. If people would like a photocopy of the book (72 pages), please let me know. It shows both MkI and MkII with ring sight, heater, muzzle and hand grip variations. Lots of great detail. I will try to get it scanned (my scanner is broken) for overseas enthusiasts that would like a copy.
Now I'll be able to line up those Fokkers/Albatros in my sights.....