Was PIK a tech stop back then, or were 747 classics from the states scheduled operators?

Before the “open skies policy” PIK was Scotland’s only transatlantic airport (politically). BA, Northwest and Air Canada are three of the mainstays I recall from my earliest ‘enthusiast’ days circa 1981. I may be wrong but I think Pan Am was staging and it’s fair to say many short haulers and USAF aircraft still use PIK as a ‘gas n’ go service’.