It was quite a few years ago while they were on holiday and mum was keeping an eye on their house. She went over and found the sliding door open, so I went over and had a look too and we called the police. I think the thieves might have still been in there when I was in their back garden. Don't know for sure though.

Security alarms are a good idea, but false alarms are a b=nuisance. I've had trouble with my smoke alarms recently. Hopefully that's fixed now.