The AM Form 78s don't usually give details of repairs - it's more a case of recording that the aircraft has been damaged and then returned to service. I checked the AM 1180 Accident Record Card (originals with AHB, microfilm copy at Hendon) and the first entry says "Part of wing broke off in air. Aircraft crashed".
A later entry reads "Aileron probably broke off in flight followed by loss of control."
The summary of the Court of Inquiry states, "Structural failure in air. CO rec[ommend]s periodic o[ver]haul by contractors of Anson. AOC agrees. AOCinC: AIB has [illegible] invest[igatio]n of [illegible] failures & accident rate very low.
AIB: Loss of control followed by structural failure. Primary cause N/K [Not Known] but evidence suggests breaking away of aileron."
There seems to be no mention of this accident in the Accident Investigation Branch reports at Kew (Series AVIA 5) which may indicate that AIB merely commented, rather than holding a detailed investigation. I'm not sure how loss of an aileron would lead to structural failure, but loss of control may have led to a dive which overstressed the airframe. There is no specific indication of the wing failing as the result of a repair, but the card suggests that aileron failures had caused previous accidents.
As far as I'm aware, records of Courts of Inquiry have not been preserved.