In reply to Mr. Lee:
For anybody else in the same position the BD cables don't fit old WCs. The WC cam heads are wider meaning there's not enough surplice wire to bend at the cam heads to hold the wires in place. Also, the link between the cable and wire interferes with the cam head function. Looks like I either have to bodge it but a new cam.
On a separate note it seems a pity that WC no longer supply parts for a four year old cam and don't offer any sort of maintenance service grumble grumble.