The other morning it was -6 and after leaving the engine running for a few mins whilst de-icing the windows, I drove off. As usual, the central locking locked automatically...but then it did it again about 30 seconds later. And then again about 30 seconds or so after that (the boot and all the doors were fully closed).

 

It continued to randomly lock for the next 5-10 minutes before finally stopping.

 

It's not done it since, so I'm assuming it was just something to do with the cold, but it's never done it before in the cold so I was just wondering if anyone else has ever experienced something similar?

Probably worth lubricating up the locks when it gets a little warmer.  Lithium spray keeps door/hinges/locks all good.  It was probably trying to lock the door when you moved off, couldn't (due to cold/stiff locks), failed....tried again...failed tried again until it eventually managed to get positive lock on the doors.