You may have a problem. When single-locked the alarm should only sound if a door (or bonnet/tailgate) is opened. And if a door is open when you try to set the alarm the horn will sound and the alarm won't set. So if the alarm sounds without a door being opened it may indicate a problem with either the alarm or the door sensors.

When single-locked it should be safe to leave the dogs in the car - I do, and haven't had any issues with the alarm sounding.

Lord Rich Tea Biscuit wrote:

Now I'm really confused...

Usually, just out of habit, I press briefly the 'lock' button to lock the car.
However, twice just recently, I've managed to set the alarm off once I have left the proximity of the car.
And for the record, this is the actual high-pitched alarm- NOT the panic horn. (Did that once!)

The manual states that briefly pressing the lock button arms the alarm, but is suitable for keeping pets in the vehicle.

I have two springer spaniels that sometimes occupy the boot, but I daren't lock it with them in it in case the alarm sounds.

Some clarity here would be a great help...
Thanks.

So it appears I have a problem with my alarm...

Sets itself off after several minutes of being locked.

It can't be internal movement, as I only 'single-lock' it.

I guessing it may be related to the alarm sounder.
I wouldn't know where to start with door sensors but it seems a number of people have experienced a similar problem and found it to be the BBS (battery back-up sounder).

My battery is fine- starts the engine quickly first thing in the morning etc. "We're in danger, we've got to get out."
"What are you talking about?"
"I've been called a ponce."