Assuming that you are still looking for a steering wheel.
1. Have tried the Post Vintage Humber Car Club?
http://www.humber.org.uk/
2. If you fabricate the steel frame, Steering Wheel Restoration Services mould the bakelite/plastic parts. They also undertake custom built steering wheels to order:-
http://www.steeringwheelrestoration.co.uk/index.php