I'd be supprised if the CAA are interested in what happened. If the aircraft went down the runway and the crew had no intention of taking off then if the aircraft happened to get into the air thats not a flight according to them.
Its a vehicle designed to fly, its operated by civilians (rather than falling under military oversight), and it did fly. Thus, on the face of it, it appears that there may have been a breach of the air navigation order - in fact, possibly breaches of many sections of it.
Whilst some folks like to bash the CAA, I suspect that if they do investigate they will take a more realistic and pragmatic approach to what happened, why, and what to do about it than would HSE, council or insurers.
A