Hi fonsini, the Vulcan had electro-hydraulic powered flying controls with each powered flying control unit being controlled electrically from the stick input via a mixer unit, what could be described as 'fly by wire'.
The electrical system being 200 volts, 400 hertz that provides the electrical power, with 8 elevon power units and a rudder unit the power comes via main busbar, which divide the power between the PFCUs.
If electrical power fails the PFCU lock valves prevent the control surface fluttering in flight, which would explain why a complete loss of power would mean no flying controls.