Good question, I don't remember. I think it wasn't filtered? The only thing I remember for sure is that when I was recently in the Netherlands, the 3IE content blockers weren't in effect. So I think it's the same when visiting the UK, falling open by default.

(Yes, I don't want to send my passport photo to 3IE, that's why I'm dealing with these blockers. And I heard that even if you do verify yourself, they still mess with the DNS records.)