I had an auto electrician out today and he narrowed it down to one of the relays, or the starter motor. He did manage to start it once, so whatever the problem is - it's faulty part, rather than not working at all. He thinks it may be the starter motor relay, but I cannot find out which terminal does what. Any ideas? Specifically - what colour/where is the starter motor terminal?
Initially, one of the fuses in the glove box was blown. I think wind screen wipers or something, I will check. Anyway, when looking on eBay before, I noticed that in one case the car used the same relay for the wipers as it did the ECU, so I wonder if it is this relay. There must be a way of finding out which relay does what?