These twintubs were especially common in the UK
Well they would have been, wouldn't they? Thanks in part to protectionism by the government, British housewives were saddled with twin tubs in post war years. Meanwhile most of her sisters on the Continent long had moved over to front loaders or other automatic washing machines.
http://www.automaticwasher.org/cgi-bin/TD/TD-VIEWTHREAD.cgi?57708
Twin tub washers Hoover or otherwise never really caught on in the USA. They were a niche market mostly for apartment dwellers and or those who for various reasons couldn't have a full sized or even portable automatic washing machine.
Now wringer washers did hold on a bit longer in the USA with production by Maytag only ceasing in 1983 IIRC. While numbers had been declining for some time, Maytag obviously sold enough units to warrant production that late in the game.
In 1950 the first industrial H-axis washer/extractors were invented, not long afterwards Miele and others introduced their own fully automatic H-axis washers for the domestic market. In the USA and elsewhere since Bendix held the patents on suspension systems for their front loader, no one else bothered to put much effort. If you didn't want to pay Bendix royalties, you had to come up with another way.... This goes a long way to explain why European housewives and others shopping for a domestic washing machine in post war years got front loaders and how they came to dominate.
This was a middle to upper housewife's laundry lot in 1950's Britain:
Meanwhile across the Pond in the USA:
Cannot say for certain, but am almost sure if either of my grandfathers gifted their wives in the 1950's with a twin tub (Hoover or otherwise), one would have a convicted murderess (or two) in the family. *LOL*[this post was last edited: 4/5/2017-14:45]