On the previous flight, reportedly down the Channel, wouldn't they have run out of "International Airspace" (ie not sovereign-owned) over the Straits of Dover (or anywhere else within 12nm of the coastline) and therefore entered UK or French airspace ?
They came over the top of Scotland, down the Atlantic and along the Channel as far as a point South of Bournemouth, then did a 180 and went back the same way.