Walter
Quite right to mention training.
The available evidence shows the status of the aircraft clearance was for training and familiarisation only (which is a formal programme phase, before operational use commences; although there can be overlap). In late May 1994 ACAS had sought to extend this, whereby aircrew were not permitted to rely on any Nav or Comms in the aircraft. Not that aircrew were told this.
This is what makes the question of flying pax so relevant. The regs don’t actually say not to do this, because they rather assume no-one in their right mind would have broken quite so many regulations to get to a point where a Mk2 was at Aldergrove.
Note this is a different issue from that of flying all VIP pax in one aircraft. Had the clearance permitted this, or if they’d used a Mk1, I’d still say it was somewhat risky, but that is just my opinion.