Given the AAIB's inclusion of both its definition of 'Ground Crew':
5.1 Maximum number of occupants authorised to be carried (including crew): Four (Two flight crew and two ground crew, i.e. engineering staff required for the maintenance of the aircraft away from base).’
and the specific reference to the the maintenance organisation's confirmation that it had sufficicient resources to manoeuvre the machine:
The maintenance organisation stated that G-CBXT was coming to them for a 25 hr inspection. They added that they had sufficient personnel to manoeuvre the helicopter into the hangar to complete this.
the inference (thanks Whirls

) is that the AAIB believes the two passengers were not authorised occupants. The CAA does seem to have turned a blind eye to the frequent flouting of this regulation, presumably because it has no material affect on the safe flight of an aircraft and, I imagine, because of the burden of proof. I can't see how carrying passengers in this case contributed to the accident, unless the pilot had a 'macho' attitude that was fuelled by his passengers' presence.
The lack of disclosure of certain (and potentially serious) medical conditions and the ease of concealment IS a worry and i agree with Big Ls that unless changes are made, pilots may continue to risk their lives and others unless better checks are put in place. I don't know how quickly a migraine can develop in a stressed environment, but it seems to me that this pilot's medical condition could very well have contributed to the accident.
TTB