The rule is very simple: You must not express, or give the impression that you are expressing, a personal view.
And yet, on the BBC Breakfast news, they push and encourage precisely that: the presenters to make little personal quips, comments and observations.
Even if it's just some stupid filler story about a dog who found a big box containing 6 months' supply of dog biscuits in the shed and ate the entire lot in 10 minutes, they'll always make some equally stupid comment at the end about the dog probably not wanting his Christmas dinner this year or whatever.
Yes, I know it's all scripted; but it's deliberately designed to look like the presenters are sharing their personal thoughts on whatever story is being discussed.