Sam Lee did say something interesting recently about how inside info was almost impossible now due to Covid. Along the lines of simply not seeing enough people from the club in person, so you miss out on the casual questions/comments which are more unguarded.
There was something a couple of years ago where the Tories had a leak from a minister, and he was convinced he hadn't. Someone who used to be work as a journo at parliament said it's not unusual. She reckoned you guess a little info, then ask one person, and their body language/reaction gives you an idea if the story is true. Once you think it's true, you can go in with more confidence, and get even stronger reactions. She said that she'd had ministers coming to her and asking who leaked a story, and she'd be thinking "it was you!".