BOAC;
would support the theory that the 'straight track' is the starboard reverse,
I'm wondering about that... - more likely the nosewheel/nose? The track described continues straight, between the main-gear tracks during the changes in direction. The rear engines would track with the main gear and follow the main gear tracks.
I realize this would mean a significant difference between heading and track at touchdown but bear in mind the airplane had just been dragging it's right wing... Also, it is difficult to tell how deep the tracks are as they track to starboard - the lateral 'g' would be significant.
The main gear touchdown point shows a relatively wings-level attitude. There are no marks "outboard" of the main gear tracks so wingtip marks would be earlier in the sequence.