Thanks for the reply bvcu.
If A&AEE could only fly Canopus by x-raying the airframe annually, it presumably meant that either it had exceeded the life/age that BAE had set or BAE were not a party to approving the modifications made to the airframe. Without design authority approval from BAE (or a suitably qualified and authorised third party), keeping Canopus flying under CAA regulations would be a very expensive undertaking indeed, and I can see why restoration to airworthiness didn't progress.
Is Canopus still taxiable or has it become a static exhibit?
As A&AEE has become QinetiQ (a commercial company) I wonder whether QinetiQ would be in a position to become design authority for Canopus (or, indeed, other antique ex-military aircraft) if sufficient funds were available? I'd imagine the costs would be prohibitive though.