What's a hidden spot in the UK that you almost don't want to share?

I’m not so sure now (as it’s become more exposed via the internet) BUT almost the whole of Northumberland used to fit the bill.  Unless you were a big lover of caravan holidays or had some kind of social connection to the area (my Grandparents fit in to both) then the chances were you didn’t have a clue about it…  I remember numerous little weekend holidays in the nineties up there with them and it often felt like myself and my Grandparents were the only ones there.  I personally hope it never becomes too commercialised but if you take British holidays for exactly what they are - and you’re not trying to emulate the Mediterranean as so many of us do - then you’ve found yourself a truly beautiful area with an abundance of walks and open spaces.