You may well be right about the origins of the vehicle, and it was a long time ago for my memory. You are definitely correct that it was in amazingly good condition, which is probably why it was chosen. We only had a few weeks to get it ready for the open day, so no time to strip the gearbox out and the decision was taken for it to be a static exhibit. We did a top overhaul and the engine ran as sweet as a nut and radios etc were sourced from various places. I believe a tube was made to replace the gun, which had been cut short. On the day, someone decided to drive it from the hangar and the brake bands disintegrated, so static it remained. Great days.