Vincent Black Knight from the saddle and a single damper replaced the twin rear shocks. The frame was also modified with the strong steel 'backbone' was replaced with a single tubular strut bolted to the steering head (which proved much weaker). The Black Knight was launched at the 1954 Earls Court motorcycle show, together with the 998cc Vincent Black Prince (an enclosed version of the Black Shadow ) and the 500cc Vincent Victor (which never went into production as only the prototype was ever built). There was a lot of interest but much of it was critical, and the Black Knight/Black Prince models
Black Prince (rocket) Aerospace author C.N Hill wrote that this declaration had been made: "Mainly, I suspect, to minimise the political damage that ensued from the [Blue Streak] decision". The 1957 concept design for a combined Blue Streak-Black Knight launcher was put forward once again, and this time received a favourable appraisal; the project was assigned the rainbow code of "Black Prince". In official documentation, the platform was referred to as the "Blue Streak Satellite Launch Vehicle" (BSSLV). The development of Black Prince was driven by the conjunction of the RAE and two private firms, aerospace manufacturer Saunders Roe and engine firm Bristol