Jackonicko, A castoring nose wheel is all you need, dont need differential braking to turn as the tail rotor does that for you. Really only need brakes to stop and occasionally to control taxi speed. All helos need a means to get about on the ground, be it Army, Navy or RAF and thats either by self contained wheels/undercarriage (Puma, Sea King) or if skid equipped by the poor groundies having to fit a set of ground handling wheels and jacking the aircraft up prior to moving (Scout, Huey).