Ferguson research also worked with Ford on their production four-wheel-drive Sierra XR4X4 and a very good system it was, too. It recognised that what with weight transfer on acceleration (and going uphill) and the general characteristics of the car a front:rear torque/power split of 40:60 was best, a feature that has been retained in the (Ford) Jaguar X-Type.
May other 4WD cars (e.g. Subaru and Audi) use a 50:50 split and actually advertise it as an advantage! Since they come from front-drive it is an improvement, but more rear would be better.
Back to the Jensen FF it had only one Maxaret anti-lock unit which was driven by the centre diff and controlled all the wheels at once, the logic being that it preserved the side-to-side symmetry, the idea being that controlling each side separately would pull the car off the road when one side was on a more slippery surface. Seemed reasonable at the time, but we don't have that now - and it seems to work.
As Carnut says few were sold and the one man I knew who had bought a non-FF Interceptor new, could well have afforded the FF but preferred what we rather dismissively referred to as the "austerity version".