the ideal solution for both the UK and the continental U.S. would've been the F-15 equipped with the AIM-54 Pheonix and its fire control and radar system.
There were proposals for such an Eagle variant but it ran afoul of military industrial politics.
If you want a interceptor with long range and long loiter then an airliner with long range AAM under the wings as suggested for the VC10 and C-135 would be an option.