Oh trust, I tell fatties that they're fatties
And if the person is smoking in enclosed public spaces, it's fine to admonish them due to the damage it can cause people.
Also be aware that while passive smoking takes longer to cause cancer, the cancer it causes is generally more lethal.
A pub landlord will probably not ban smoking, because the smokers would just go elsewhere losing them custom. It's important that the Government sets the standard as a requirement, to ensure that there will be smoke free places for people to enjoy.