It was discussed at length in the original thread. It seems to have been either fog or dense low cloud.
It dispersed the further North he flew.
He eventually caught sight of the tops of the very recognisable Eildon Hills, which apparently gave him a clue to his location.
It does appear though that fuel starvation brought him down
Without a doubt now, it has been revealed that he was definitely on some sort of Intel or Recce Mission, which goes some distance to explain the story varying from a Norwegian in Hurricane to an American in a Spitfire as well as his swift departure from the scene, almost directly to RAF Turnhouse.
He retired as a Senior Intelligence Officer in the US.
Amazing how close some on the thread came to figuring this !
(Seems that the spooks are still interested in a cover up. Messing with the links on the thread) 🤪
El Grifo