Cyclist who saw accident happen, now on BBC Radio 5...
He says...
...realised subsequently it was very quiet, tail dropped, nose rose up, then it descended fairly steeply into the field at low forward speed.. Estimated height at which all this happened was 80m (~250')
Regardless of power levels, is still looking like this aircraft entered a fully stalled condition.
Despite the tragic loss of life and no doubt many spinal compressions, fractures and internal injuries, this Boeing 737 looks like having allowed a large proportion of passengers to survive what was undoubtedly a very high vertical descent rate.