I was thinking the same thing. As I understand it it's possible only to do for subdomains. I suppose one way of doing it is with some kind of script that links

I was thinking the same thing. As I understand it it's possible only to do for subdomains. I suppose one way of doing it is with some kind of script that links up to a prehosted theguardian.com so the cookie is set from where the js is included from.