Fallon's rather unlucky, I think. Happened long ago, a one-off (unless there are other cases I haven't heard of), she objected, he apologised and didn't do it again. Exactly the opposite of Adam Sandler's behaviour, where he just did it again. Sandler's a clot, but Fallon's been harshly treated.
"She made clear it was unwelcome and he rightly apologised 15 years ago."
Ms H-B's version of events is that she quietly threatened to punch him in the face if he did it again. He apologised and the matter was closed as far as she was concerned. She did not name Mr Fallon in recent revelations about the event.
gay man's hand on straight woman's knee? Presumably no hint of a sexual approach and probably no hint of asserting dominance over her either. I doubt that a woman would complain under those circumstances; but I rather doubt that a gay man would do it in the first place.
Well, just look what Tim Fortes said when he was in charge of the Whips office under Ted Heath ," He and Ted kept a dirt book about MPs Private lives ,to turn into their political advantage."