Direct track
The FPL published by Heathrowairport is consistent with the track on FR24.
It is interesting to observe the track on FR24 when the aircraft reaches the French coast. At that time the traffic is not important and I believe that the ATC gave a direct course as a shortcut. A classical way of control. The plane was on the UN870 between ROTIS and MAXIR at 380 and has likely received a direct course to OKTET or IRMAR (44.80 6.79 ). This is the latest waypoint of the French FIR. The direct course is a 25 degree course. If you draw a line from the position where the aircraft initiated a left turn you can easily see that. This track is exactly the one that brought the aircraft to the crash site. Shortly after initiating this left turn the aircraft started to descent but kept its initial heading until the end of the flight.