In the US (not applicable to UK, probably). 91.109(c)(3):
Except in the case of lighter-than-air aircraft, that aircraft is equipped with fully functioning dual controls. However, simulated instrument flight may be conducted in a single-engine airplane, equipped with a single, functioning, throwover control wheel, in place of fixed, dual controls of the elevator and ailerons, when -
So limited to the Bonanza and it's ilk. No rotorcraft.