About 10 mins into my drive to work on Thursday, the ASR warning light came on. Bit puzzled and annoyed, never had any gremlins before but a busy day so couln't do much about it. Driving home, same thing happened. A quick search on the forums here suggested a broken "load signal" cable. Same again on Friday confirmed my suspicions so a quick check under the car this weekend revealed the offending broken wire. A couple of hours, some extra lengths of wire and a few connectors later and all is well again

Thank you Briskoda for saving me a lot of time, hassle and expense.

As an aside, can anyone explain, in fairly simple terms, what this load signal cable actually does?

It's the alternator sense wire. If broken the alternator fails to charge the battery.