Agree with BVCU.
At the end of the day the aircraft was not legally fit to fly. It had numerous failings in regards to it airworthiness which means the Permit to Fly obtained was done so by false representation by the maintenance companies for several years. Do the CAA still carry our prosecutions?
This coupled with the air shows failure to adhere to basic health and safety by failing to complete through risk assessments should mean that they are also investigate and prosecuted by the HSE.
Agree the pilot was probably not aware that the aircraft was not as sound as it appeared. After all if you take a car to a garage for a service you take the car in good faith that all the maintenance has been carried out to the correct acceptable level. You would not then carry out a service yourself to check.
The main question is have the police been provided with the aircraft records so that they may look at these and gather evidence or are these now not available to them. Why can't the police have the actual maintenance records and flight test data direct from the maintenance companies. They should also have access to the aircraft if required, after all how are they to obtain evidence if they aren't able to do this. Obviously they will need to employ specialists to help them as I doubt anyone in the police force will be a qualified aircraft engineer or a fast jet pilot with the relevant experience on type.