Originally Posted by
renfrew
I have a summer 1978 timetable which shows BE 625 as a Geneva-London Trident.
Yes, it looks like Wikipedia (from which I took my information) is wrong about the BE designator being withdrawn in April 1977.
This site quotes it as still being in use in Winter 1977/78 and your Summer 1978 timetable backs that up.
So the designator change for European flights must have occurred at the start of the Winter 1978 season, as
this timetable confirms.
I remember vaguely that what happened was in S1978, flight numbers were rationalised across BA, hence the OP's flight number change (but still retaining the BE prefix) and then the designator changed from W1978 onwards, so that BE577 GVA-LHR changed first to BE625 and subsequently to BA625.
Incidentally, the legacy of that system continues to this day, over 40 years later: BA LHR flight numbers from 1 to 299 are longhaul, and departures are odd-numbered, whereas shorthaul flights are 300 upwards, with LHR departures even-numbered.