I can assure you the pilot was IMC qualified, and it was his own aircraft, not club owned.
I'm not going to speculate as to what I think happened, merely stating that the weather was guff at the time which is apparent from the historic METARS. These are easy to read in hindsight and the TAFs may have shown something different but from memory of my brief that day the Form 215 showed crappy weather to the west, a nicer patch over Eastern Scotland and either a warm or occluded front out to the east moving west at about 10-15kts. It may have been the pilot thought he saw a window in the afternoon where the nicer patch would be over his destination, as it happened the winds aloft were not even close to forecast that day.
I'll leave it for the experts to figure out.
Regards
UA