On reflection I probably forgot to lock it!
I have forgotten previously... distracted, carrying things, being talked to, thinking of other things...
The ironic thing is, there was a Disklok fitted and proper anti-ram posts across the drive, so stealing the car would have been tricky! As, has been said, probably chancers doing what they do best (good for fuck all else).
Thanks MarkyM for clarifying how the auto-lock works; I’d read about it previously but like many things, had forgotten how it worked! There’s a theme here... me forgetting things... must be getting old!
So, cameras next, then!