I’ve had a look at archive material and the F90 was certainly sold in the UK in the late 1960’s and into the 70’s.
The British Tractor and Farm Machinery Journal in 1968 says it’s a new machine and is “fitted with eight forward and two reverse gears, 2 cylinder 479cc vee-twin 4-stroke overhead-valve unit having an output of 9hp at 3000 rpm. The rotary cultivator unit is detachable, and a special PTO point is incorporated with a choice of four operating speeds”.
The distributor in 1968 was listed as Honda (UK) LTD, Power Road, Chiswick, London.