Okay. I've tried the disconnect the battery thing. No joy. Even if you reconnect with doors closed, the alarm reactivates on reconnection. If you disconnect with door open, alarm re-sounds.

The anti tow alarm button is irrelevant in this case because I cannot switch off the normal antitheft alarm. i.e. when I manually open the doors with key, the alarm sounds. Engine starts then dies. There must be a manual override to actually disable the alarm? most of my cars have had a keyturn on the alarm box to disable. But I don't know where the alarm is to even try and see if it has an override.