Returning Concorde to flight - things to do:
1. Obtain a Concorde, along with a suitable raft of spare parts, including engines (the easy bit!).
2. Recruit a team of professional design engineers, stress analysts, material scientists etc, with enough relevant technical background in their CVs to convince CAA that they can act as Design Authority.
3. DA team to review the stressing, fatigue life, corrosion performance, etc of every component in the airframe, both in isolation, and in conjunction with every adjacent structure.
4. Build a comprehensive structural design record for the design.
5. Repeat steps 2 - 4 for each of the following systems: (a) Engines, (b) Electrical System, (c) Hydraulics, (d) Avionics and Instrumentation, (c) Fuel System.
6. Create and certify a CAA-approved facility, and recruit specialist engineers, to strip, service and rebuild at least 4 Olympus 593s to flight-worthy condition.
7. Do another 1001 things that I haven't thought of....
8. Congratulations! You are now at the position that VTTS were in when they first started their fund-raising.
9. Do what VTTS did, bearing in mind that your aircraft is far more complex than theirs, and that it has
not been cared for with a view to return to flight since it's retirement from service.
Anything can be done at a price. In this case, I'd have a guess at a minimum of about £250M?