Great Phil, lot's of interesting stuff.
The "bum roll" was a widely despised bit of kit. I threw mine away, as did most tank crews. The infantry did need it but tended to fix it above the kidney pouches.
The "flaky tank" - museum exhibit, not really appropriate for an operational tank. Does raise an interesting point about "chipping" though. It can be grossly overdone. Yes, a badly applied coat of paint may have flaked but in general, scratches were about all that you saw. The only generic examples of military kit where chipping is really appropriate are the late war Japanese Air Force aircraft, where paint quality was a real issue. On Cold War British tanks, probably need to be very restrained indeed.
Mk 11. I hope someone does offer a STILLBREW upgrade. If anyone is contemplating doing a Mk 11, they will also need to consider replacing the light projector with TOGS (Thermal Observation and Gunnery System).
The NBC pack was also upgraded from No 6 to No 11 but the changes were internal. By the time the Mks 10 & 11 were in service, the Army was fully converted to the CLANSMAN radio system, replacing the earlier LARKSPUR. Externally, there were changes to the antennae, antennae bases and mountings.
We also need to find a source of denims (one piece tank crew coveralls), black for the World's oldest armoured regiment and green for the
Donkey Wallopers sorry, old habits, the Cavalry.