Bookworm- I think that is as far in agreement with the events as I can see. Flight recording then was extremely primitive and caution should be attached to these readings.
PickyPerkins, I've been thinking about that excerpt from the CAB report and I think it is simplistic. An updraft will induce an instantaneous weathercocking nose down. Due to the inertia of the aeroplane, it will tend to continue on the same horizontal path with increased AofA. When it comes out of the updraft, its AofA may even be negative, giving a strong pitch up momentum- if it then rapidly moves into downdraft territory, there will be a cumulative effect and it will provide a very powerful increased weathercocking nose up effect. To counter this, anything up to full nose down control may have been applied. I think the catastrophic event occured just after 12.20.