Help! Any electrics experts out there?

[Humbug]

No, the cable was initially attached to the plug using the crimp connectors supplied. As it didn't get hot I then soldered the wire to the supply cable, with no difference. I then attached the heating wire directly to various batteries and power sources with again, no difference. Replacing the wire has solved the issue so there must have been a problem with the wire?

 

[Humbug]

Finally stitched the new length of wire into the jacket, soldered and heat shrinked the connecting cable (I don't like crimps), started engine, plugged liner into auxilliary socket and the result is - toasty, toasty! Voltmeter reading across the heating wire gives me 13+ volts with the engine running.

Once again, many thanks to everyone for their input and especially to Richard for his help and for sending me a new heating wire.