Although the BIOS had become corrupted somehow, it wouldn't have taken a rocket scientist to have noticed that the laptop was running Win10 'anniversary', not the >2 year old version of Win8.1 with which it was returned, grubby paw prints fully embodied.
After I went back again to collect the laptop after the store had reinstalled Win10 plus all the updates, it took me a couple of days to remove all the junk 'start' icons and other 'things-for-kids' which the puerile Win10 rams down your throat, reinstall the anti virus, reinstall MS Office, create desktop shortcuts, restore the desktop background, restore the HomeGroup, reinstall the printer etc etc....
To be honest, most of the PITA is due to Windows-bloody-Ten! I far, far preferred the functionality of WinXP, although Win7 is almost as good. But Win10 and Office 2013 between them really are very poor substitutes as far as HMI and funcitionality are concerned.
And don't start me on that Cortana bolleaux!