Yesterday I went to start the car and found a flat battery. Install of jumping it, I decided to trickle charge the battery back up. It fired up fine - bit of HA noise but that quietened down once it had warmed up. I warmed it up for 10-15 mintutes, checked the fan was cutting in OK. Excellent. Check the tyre pressures tomorrow (now today) and it's ready.
I no sooner got in the house and I was rewarded for spending some time with Oscar. He decided to call me back with the alarm. I went out checked the doors and windows - all good. Reset and went back inside. 20 minutes later he wanted more attention! I went out and locked the car without the alarm.
It looks like I need to do some diagnostic. I'm going to finish this cuppa and go out with the computer to see which sensor is triggering the alarm. I'm suspecting bonnet sensor.