For what it is worth There are changes being proposed by the CAA and under consultation by industry at the moment that could well see major changes that will lead to the operation of comercially based flights in the likes of Spitfires.
And I quote
and it provides a framework that could be used to support limited commercial operation of ex-military aircraft in the future.
See
http://www.caa.co.uk/docs/2537/Annex...%20Comment.pdf
And
Proposed Amendment to BCAR A, CAP 553 and BCAR B, CAP 554 | Consultations and Responses | About the CAA