Rolls-Royce Test Pilots
Genghis,
As someone who did work for R-R, specifically the Flight Test Centre, for many years, you are almost 100% correct in your thinking. However, there was another aspect (up until 1994) with the in-house testing of development engines/systems in aircraft, usually supplied by MoD(PE), suitable for the task.
The original Flight Test Centre (FTC) at FZO was basically divided into two areas; Flight Test - consisting of TP's, FTE's and Instrumentation Specialists; Engineering - who not only maintained the aircraft but, in the majority of cases, converted them into appropriate FTB's for the task. This usually involved structural and system modifications, as well as the installation of (latterly) MARS & MODAS data recording systems.
During my involvment in the FTC (1973-1993) we had many aircraft pass through our hands but some of the more memorable were;
Vulcan FTB with (underslung) RB199
Harriers for FADEC development and for the up-rated Pegasus 11-61
Lynx helicopters for FADEC and Gem development
Sikorsky S70C for RTM322 development
In addition, we also were closely involved with the RB211/VC10 FTB and in later years with the USN Sikorsky SH60B/RTM322 evaluation programme.
Apart from those types mentioned above, we had Phantoms, Jet Provosts, MB326 & 339's, Westland-30, HS125's and numerous other, short-term, FTB aircraft pass through our doors, the primary purpose of which were to carry-out our own in-house development programmes. Sadly, this was stopped in early 1994 and, although R-R retain TP's and FTE's, since that time they only carry-out their role in conjunction with the airframer or customer.