BBC doesn’t show ads in the UK (bbc.co.uk), but the international edition (bbc.com) does. The site looks quite different, and automatically redirects based on geolocation.

(Annoyingly it’s also stored in a cookie; if you travel frequently, you can get stuck in a redirect loop.)

I did not know that. I have just checked and my UK ISP provided DNS does not even resolve bbc.com!