It's quite incredible the rivalry that continued to exist between the sub brands within the British Leyland stable and how ultimately detrimental that thinking became: That not only Triumph had a whole series of engines that weren't available to the rest of the group* but they even persauded management to subvert budget to design and build their own V8 for the Stag which was after all a relatively small volume, niche up market sports car rather than adopt the tried and tested Rover 3.5 or launch with the straight six 2.5 from the Triumph saloons
* ok the Triumph 1.5 was admitedly used in the MG Midget