As an aero modeller in my younger day, I think it was actually 27 MHz in FED's day. In any case, HF frequencies don't go as high as 35 MHz; the RAF HF sets we had could transmit betwen 2-30 MHz.
IIRC, 35 MHz was allocated to model aircraft later. I've still got a functional 35 MHz RC set somewhere, and remember upgrading to it from the earlier type sometime in the 1980s.
A few years ago I was transiting the Heathrow control zone near Brent reservoir at about 1100 feet, when a large high performance aerobatic model aeroplane, complete with tuned pipe, appeared right in front of me. Obviously, it didn't collide with my aircraft, but it was very close.