cazatou,
there were a large number of eyewitness reports of the aircraft over Antrim, reported the aircraft at very low level, typically at 100 ft AGL.
Is this another case of your use of selected information to distort the truth?
I can't say I know the area but I am sure that a direct track from Aldergrove to the Mull passes over some pretty high ground. Surely they would have been at a much higher altitude over most of Antrim, even at 100 ft AGL? The wind could therefore have been at the higher level over that sector.