Alaskaman: I think what you are looking for is a UK Air Navigation Order Article 33 Permission to carry out such a flight
Take a look at this and see if this helps.
https://www.caa.co.uk/Commercial-ind...-an-exemption/
This page provides information on how the CAA may accept applications for and issue Exemptions and Permissions concerning overflight of aircraft with non ICAO compliant registrations and airworthiness certificates.