Getting Chris Bryant MP on your case must be like having a small but determined dog bite your trouser leg and not let go. No matter how loud you shout you can't get rid of him. And you can't kick him with the other leg because you'd fall over.
David Cameron knows what it's like. For weeks now Mr Bryant, the Labour MP for Rhondda, has been snapping at him, determined to make him reveal all the texts and emails that passed between him and Rebekah Brooks, and between his former press secretary Andy Coulson and anyone at News International.
Mr Bryant says that these are – he quotes a civil servant – "scurrilous and deeply embarrassing".
A handful have seeped out, including one about a high-spirited horse and a confusion over the initials LOL in text speak. Mrs Brooks admits to having broken down in tears after hearing one of Mr Cameron's conference speeches.
Mr Bryant keeps raising the matter at prime minister's questions, but Mr Cameron flips him aside, demanding an apology for some past attack. So on Tuesday Mr Bryant took his canines to Westminster Hall, the mini-parliament where MPs can raise issues in front of a tiny audience.
He said there were "profound discrepancies" in the prime minister's evidence to the Leveson inquiry. Mr Cameron had refused to answer parliamentary questions, in defiance of the rules, "and his silence speaks volumes". He came as near as possible to calling him a liar without actually calling him a liar.
Did the missing texts and emails show a much closer relationship with the News International people than we knew? Had it been going on much longer? He had taken advice from a lawyer. Was the lawyer paid by the taxpayer or by Mr Cameron himself?
Here the chairman, Philip Hollobone, the Tory MP for Kettering, decided to step in. Mr Bryant had come "perilously close to crossing the line in trying to impugn the personal behaviour of the prime minister". Mr Bryant took time off from savaging Mr Cameron to savage Mr Hollobone. How could asking if Cameron had paid for his own lawyer "impugn" his behaviour? "I think this chairing is rather dubious. I have made no imputation against the prime minister!"
He let go of Mr Hollobone, who kept stumm, and resumed chewing the prime ministerial ankle. Emboldened, he implied that various decisions about BBC finances were connected to the Cameron-Brooks friendship. Everyone had a right to privacy, but the prime minister made executive decisions. He could only conclude that "the material may be incriminating".
Mr Hollobone did not even rise to this, possibly feeling that a few more bite marks would not beautify his calf. "This conduct would make most people in the country question the bona fides of the prime minister!" Mr Bryant moved towards his triumphant peroration. "However long the prime minister puts his fingers in his ears and screams 'la, la, la!', the material will come out. It's the cover-up that does for you in the end!"
The minister replying, Ed Vaizey, flannelled pointlessly. At 11 minutes, it was the shortest filibuster I've ever heard.
