I'd be interested in your source. I can't find anything in the official airport history or airport documentation at the time, any contemporary magazines, in my log books - I lived 6 miles out on the approach at the time - or any other source including my memory.
Had there been such a service it would have been of great interest and I would have been on the domestic pier to see the flight at least once as, in those days, the piers were open until 22.00, even in winter.