Step Turn, if you are going to quote from the AAIB, you should quote the complete segment, which goes on to say:
Witness marks from any restriction would have been difficult to detect, even without the significant damage from the ground impact. Thus it was not possible to determine if there was any damage or witness mark that might have arisen from a control restriction in the cockpit.
In the summary at the end, the AAIB then states:
The pilot stated that he had a rudder control restriction. The inspection of the wreckage, and in particular the flying controls, revealed nothing conclusive to suggest that there was a control restriction. However, given the level of damage sustained by the aircraft, the possibility of a control restriction could not be eliminated.
FBW