To be a little pedantic: XE 531 was not a "T12" , just Mk12. This airframe had no training role, but was used for the development of some avionics for the TSR2. This included a HUD for the TFR system, and there was also a vertical camera in the nose. There was also, as noted above, a FBW system. Had TSR2 gone ahead, there would allegedly have been some more built as T12 - yes, for training this time - as part of the TSR2 conversion course.