General Won't start on key but will if starter shorted.

[Honestyblinds]

2007 2.0 came out to it the other evening after driving to see a customer. Turned the key and nothing happened. Everything electrical worked. Battery was strong. I guessed at the starter so rocked it in gear and then the key worked (but I think this was a coincidence). I drove home but when I switched off, it wouldn't start again, rocking in gear or not. I bought a new starter motor and fitted it, still the same. If I short across the starter terminals, it fires up and runs no probs. Once started, I hear a single 1 to 2 second beep inside the cab. Under the bonnet there seems to be a whistle coming from near the abs unit, or thereabouts. Any ideas? I'll probably run a push switch for now but I'd like to get it sorted.