Given, the brown bear was the traditional UK bear, pre-Roman times.

It is rather hard to imagine them in modern day UK. The population living in areas they are introduced, would def need to be trained and prepared.

I cannot see that happening due to lack of support. Wolves we know as historical fairy tale villains. But in reality they avoid humans where they are still native. Brown bears have more fight than flight when taken by surprise. And don't tend to have the nervousness to avoid the interactions themselves. Hence, why travelling noisily is recommended in areas they reside.

Pretty sure everyone knows the bells on shoes joke.