So the insurers are 100% certain that the aircraft complied with the ANO then and was fully serviceable at the time.
Even though the AAIB have queried that the aircraft had out of date cartridges fitted and therefore doesn't meet the ANO which in turn raised the question that should the PtF been applied for and granted.
If it is discovered the aircraft was flying and shouldn't have been. Does this mean it is the fault of the CAA who issued the PtF for not undertaking through checks or the person/organisation applying for the PtF and declaring the aircraft had complied with the ANO etc.
I am presuming that the CAA when a request is received undertake a check of the aircraft itself and the books to confirm all is in order.
Think the insurance company have paid interim payments whilst they await further information as to cause and therefore liability, they will make a counter claim against another policy if there are other factors I am sure. As I would have thought non-compliance with the ANO would invalidate the insurance.