Well Chris Scott - it seems we both remember the event and as a direct result the system changed. Any high speed taxi checks had to be crewed and prepared for a normal flight with a load sheet and 2 pilots. For anyone interested in this particular event the aircraft became airborne when the flaps were selected (don't know why). It was out of trim and the pilot managed to stay airborne narrowly missing the Gatwick control tower - the old one! - before completing a very hairy circuit and landing safely. A very narrow escape. I am not aware of a similar occurence since - fortunately.
Oh and by the way I didn't think The Hamattan reached Libreville.