At PMQs on 1 December 2021, Keir Starmer asked: “As millions of people were locked down, was a Christmas party thrown in Downing Street for dozens of people on 18 December 2020?”
Boris Johnson replied: “All guidance was followed completely in Number 10.”
That's a lie, TTT. Not an opinion.
If it was an opinion, he would have said “In my opinion, all guidance was followed completely in Number 10” or "To the best of my understanding, all guidance was followed completely in Number 10” or even the tactic he later started employing, “I am reliably informed that all guidance was followed completely in Number 10.”
But he gave a bald statement of fact that was wrong, when he knew all along what was going on in the place where he lived and worked and partied. He lied about it.
In this case his standard tactic of evading the specific question worked against him. Asked about an actual event, he replied about Downing Street generally, with a whopper of a lie.