Sip rear disc brake problem

hi all ive got a sip rear disc brake with the master cyclinder
bolted to the back of the frame near the spare wheel like
the ones shown in scootering a while ago .
the problem is that ive snapped the cable and i dont know what
bike the cable came of to replace it i dont real want to have to send of just for an inner cable as coast would be well over the top
[:itchy:]
GRUMC
LOST BOYS SCOOTER CLUB SHEFFIELD
est 1986