It seems logical to me that the UK 64 should have a vertical handle (if viewed with the cleaner stood on end) as this was in keeping with the earlier cleaners, and in my opinion added to the budget look of the cleaner as it was very similar to a good deal of others on sale at the same time, such as models in the Goblin range. However, as time progressed it would also make sense of course for the cleaner to go for a horizontal handle, such as the 77 did, and to me it looks that little bit more up to date.
So why then I wonder did Electrolux revert to a vertical handle for the long duration of the model 87 and later 96? The only advantage I can see to it was that it incoprorated a very simple catch to hold the front cover in place, but then a simple buckle or clamp over the top would have done, as was seen on the Goblin 555. Even that cleaner always stuck me as more modern in style than the Electrolux 87, with it resembling an Electrolux 302 rather than the 87 which it was competing with.
Personally, I expected the 87 to have continued with the handle as it was seen on the 77.