I agree with Pulse. Before posting again on weather or altimeter setting please go back and read all the other entries on this subject.
If you then still have something new to say on the subject, feel free to raise the issue.
Otherwise, please, please stop going around in circles.
I think it has been established beyond reasonable doubt:
1. The crew approached the Mull in poor but perfectly legal VFR. (Holbook)
2. The crew must have been ( at least technically) IFR at point of impact. ( Lighthouse Observers)
3. There is no way of knowing if the crew ever entered cloud and lost forward visibility.
Caz, as a pilot you must know that if the observers and the driver could not see the helicopter, they had no way of knowing the conditions the crew were experiencing. You can sit in a control tower reporting zero visibility while 100metres or so from you there are aircraft landing having picked up the lights at 20 miles.
That is the nature of cloud / fog banks.