The Vulcan had the same system of powered flying controls as the VC10. Mechanical input to a servo valve, which ported hydraulic fluid to one side or other of a piston to move a control surface. This hydraulic pressure was provided by an ac electric motor on each PFCU, no fly by wire until using an autopilot. The elevons used a suitable system of bell cranks a pulleys in a mixing box to convert the roll and pitch movement of the control column into a mechanical signal to the PFCU! This system was taught to me at Halton in the early sixties, before the VC10 came into service, so was not state of the art even then.