AAIB reports are admissible in Civil (ie liability) proceedings - as per Rogers v Hoyle
They are not admissible in criminal proceedings nor is the material obtained in the course of the AAIB investigation. It is annex 13 'protected' material. See also EU Regulation 996 0f 2010 Article 14 1(d) and Regulation 25 of The Civil Aviation (Investigation of Air Accidents and Incidents) Regulations 2018
The AAIB report was not used in evidence during the Shoreham trial