My father was very much involved in the inquiry into Jack Overbury's accident, having done the repair scheme for the centre section of G-AOUS following a belly landing on an overseas sales tour.
Jack was coming out of a loop when one wing failed ( upwards). The other subsequently failed ( downwards) . Haraka Senior spent many sleepless nights as it was obvious where some of the initial suspicions lay.
A couple of boy cubs then found the nosewheel doors up in trees in a copse some way from the wreckage.
This put focus on the nosewheel bay, when it was ascertained that a solid grease accumulation had caused the noseleg to come out of the uplocked position in the 'g' of the pull out. The nose doors consequently started to open and this caused a rapid pitch up sufficient to break the main spar. The doors then fluttered down away from the rest of the aeroplane.
Tests were subsequently done building up the external profile of the doors with wood on flight test, revealing the consequent increasing pitch instability.