the idea of a rocket motor boost seemed right for the time span and it's one the RAF toyed with in the 50/60's
Chris
Chris
You've got me thinking about building one of these now, so I've been doing a bit more research on British rocket motors available in the 60s. As mentioned above the Stentor dual chamber motor was fitted to the Blue Steel missile - this had a large chamber with a fixed 25,000 lb thrust and a smaller chamber throttleable between 1000lbs and 6000lbs thrust. The smaller chamber was used as the basis for the Gamma engine as fitted in the Black Arrow satellite launcher, and a pair of them were also fitted into the back of South African Buccaneer S.50s, where they developed up to 8000lbs thrust each ( so there is a precedent for aircraft use for this engine

) - in this form they were called the Bristol Siddeley BS.605 engine.
For an interceptor Vigilante I could see either the full Stentor being used ( for a model the back end of the Blue Steel from the Airfix Vulcan could provide a basis for the conversion - now where did I put that spare Blue Steel

) or multiples of the BS.605 as fitted to the Buccaneer.
These engines burned High Test Peroxide and kerosene - in the Buccaneer the kerosene was drawn from the aircrafts normal fuel tanks while the HTP was stored in special tanks. The same could be done in the Vigilante, with the HTP tank located in the weapons bay ahead of the rocket motor.