Thanks for your replies.
In 1998, I had a Candy-based Hoover "Optima" D840 myself. It was quite a good dishwasher, if a little noisy. It had a two-speed motor, and I always left the "Super Wash" switched on. Candy machines had their version of it, known as HPS - High Performance System, or some such name.
The old Hoover "Autojet" with the rotating basket sounds very interesting; a bit like the dual wash system of the early Hoover Keymatic washing machines. I dare say that the basket drive system might have incurred a high failure rate.
I googled for "Hoover Autojet", and one of the few results led me to a Patents site which had an old patent for rinse-aid with 'anti-redeposition properties', invented by Lever Brothers (no doubt later sold as "SUN"). The main test machine they used was the Hoover, in addition to Bosch, Miele and Indesit. The Hoover appeared to have the edge, in terms of rinse-aid dispensing capacity.
The old Colston looks very nice... does it still operate?