So...the exact scenario is as follows and I have just managed to replicate it (MG 4 Trophy long range, 23 REG)
1) Unlock the car and start it up (press the pedal or something, pretend you are taking it for a drive)
2) put it in parked position as you would at the end of the drive
3) get out of the car (with the key) but DONT LOCK the car
4) the lights remain on for some time and the mirrors are unfolded
5) after a while the lights turn off, mirrors are still unfolded and car remains unlocked despite no key inside
6) go to the car - it is unlocked so dont try to unlock it again, open the boot and put a key inside a handbag, any other bag in it and close the boot (if it matters - on the right side and close to the boot door)
7) after a few seconds the car locks itself
Is this the expected behaviour? Would be interesting if anyone here can replicate it with their car?