Re: "But don't you have to pay another £70 to do so?"
Misread the article - I didn't realise that these were Window 10 S machines. I thought they would be running at least Windows Home for that price. Just checked on my wife's laptop. Windows 10 Home to Pro currently costs £119.99. So yes - you can upgrade, but as soon as the free upgrade period is over it could cost a lot extra to unlock what we'd consider basic functionality.