Alarm constantly on

Hi all, I've got a 2002 Discovery TD5 and tonight when I returned to it, unlocked as usual and when I got in the alarm went of constantly, bang doors shut and it went off but as soon as I moved inside it started again, very embarrassing! I undid front grill and disconnected both sounders and came home. It locks and unlocks fine and immobiliser light on dash flashing as normal. I guess it may be an earth fault but where?

No idea, but isn't it bad that someone potentially stole your car after setting alarm off twice, slamming doors, and tinkering under bonnet, did any one react or call plod?

I've never seen anyone react to any car alarm anywhere ever..

The alarm on my Disco II works off a different sounder, that's near the bulkhead.
Think it was fitted there to stop baddies just disconnecting the horns behind the grill

There's 2 sounders for the alarm behind the grill which I had to disconnect, the steering wheel car horn works normally. I unlocked with the fob as normal and when I got in and rocked the car a little it started. No one reacted as they new it was my car but they all were in a sudden rush to get home!