Carpets
Although fitted carpet has been much more popular in the UK in the years since the war, it's taken a very long time to get to the point where all could afford it. So much so, even by 1959 a good deal of homes would still have had a hard-floor surface, with a rug or carpet square over it at best. Having said that, rooms would generally have been rather small and mopping them would have not been much of an issue. Polishing was what took the time and effort, which would explain the immense popularity of the Hoover polisher & later shampoo-polisher.
Given that this hard-floor cleaner was readily available in Europe, I too am surprised that none made it to the UK. I am inclined to believe that they would not have sold well, what with all I just said about mopping floors, and I assume they'd have cost quite a lot of money. Families in 1959 had an awful lot to aspire too, therefore I think a wet-floor cleaner would have been way, way down on the wish-list.