I'm certainly no expert in this, but I seems to me that the picture on P.30 of the pdf report is quite revealing. It seems to show a large trace of unburnt fuel just left of the centreline of the runway, then a long scorch mark that starts just left of the centreline and runs more-or less parallel with the centreline for several tens of metres (or more?). It then reduces in size and drifts leftwards towards the runways edge. It eventually peters out off the runway.
My interpretation is that the aircraft was running straight at the time of the tyre burst and immediately afterwards. The straight track initially after ignition suggests that the aircraft was still running straight, approx. parallel with the centreline.
The track drifts left when the trail reduces in size, presumably because the aircraft was airborne, taking the flames away from the ground.
This seems consistent with the view of the investigators, and contrary to the Observer article? The aircraft was running essentially straight after the tyre burst and even after igntion. It rotated and started to climb, when loss of power on the left together with airflow interference into the engines caused a left yaw.
Is this interpretation reasonable or completely off the mark?