The first UK upright cleaners with the ability to switch off the roller brushes would have been one of those industrial Sebo machines, discussed on another thread. They date to the late 1970's, although I think the brush roll would only stop when either the handle was raised or if the hose was taken out for use. I don't think the cleaner could be actually used to clean in an upright fashion with the brushes off.
The Panasonic MCE5- series did not arrive until the early part of 1992. After the Hoover Turbomaster, these are the next cleaner I can think of to have the brush roll on / off facility to allow the cleaner to be used upright with suction only. However, I do believe the first type of cleaner to have that feature would have been the Hitachi CV55, at least I think it is 55, someone showed photographs recently of an excellent example they'd bought if that helps. Although I am sure a few people would have used the brush roll on / off switch, I wouldn't expect it to have been life or death for most users, nor do I think it would tip the balance between buying an upright over a cylinder, because upright lovers who wanted to vacuum hard floors with an upright cleaner would probably do so irrespective of whether or not the cleaner had the brushes whizzing round.
Interestingly, Hitachi did not continue with this facility on any other cleaner made for the UK market. Maybe they thought it was redundant. Of course the Turbomaster was unique in that it also switched off the roller brush when the cleaner was stood upright, by making good use of the same parts which controlled the brush roll for hard floor cleaning.