What are parliamentary whips and what powers do they have to ensure MPs behave?

The Conservative MP, William Wragg, has claimed that colleagues who want to trigger a no-confidence vote in the prime minister have been intimidated and even threatened with having funding withdrawn from constituency projects.

To some, these claims are explosive. But others claim that all of this is run of the mill.

“Whips strong-arming colleagues now constitutes blackmail,” said one MP (supportive of Boris Johnson) to me. “While I wouldn’t condone direct intimidation or threats, Wragg’s statement is laughable.”

So, what is the truth?

How persuasive, or should I say forceful, are those MPs – known as the parliamentary whips - whose job it is to ensure that their political colleagues behave?

The answer to that question is the stuff of legend – with fictional characters like Francis Urquhart in House of Cards (later Frank Underwood in the US version) making us all think - very, very persuasive.

And to be fair, it does seem to have once been a little extreme.

I remember being told about an incident in the early 1990s in which one MP was physically pinned to the wall and threatened by a whip who was going to make sure that he voted in line with his party.

And who hasn’t heard of the little black book- that notebook listing all the naughty things that every MP has ever got up to?

But look – it is clear to me from the 12 years I’ve spent covering parliament for various newspapers and broadcasters, that times have changed – and with them whipping operations have calmed down too.

That is not to say that threats are not used when whipping – they clearly are. The clearest one is to warn the MP planning to rebel that he or she is kissing goodbye to any hope of a ministerial job.

And often (although not always) that threat is followed through on.

“Saying ‘this might not do you any good’, is part of the job,” said one source who has worked for a whip under several party leaders.

But do they go further than that? From what I’ve seen – the answer to that in recent years – has been largely, no. Whips are more likely to opt for carrot, than stick, according to those I speak to - getting wavering MPs time with secretaries of state or even the prime minister, and perhaps offering them money in their constituencies.

But before this government, I certainly never heard of threats to withdraw funding from constituencies.

Anushka Asthana explains what whips do - and what powers they have

As to whether it is really happening – it is hard to be certain about that.

The PM says he’s seen no evidence, and senior sources close to the whips operation deny it too. And, to be fair, MPs I’ve spoken to – even really rebellious ones – say it hasn’t happened to them.

But Christian Wakeford, who defected to Labour, said he was threatened over money for a local school, while two other Tory MPs insist they’ve seen it happen to colleagues.

Either way, its caused anger on both sides – and more tension in the party – is probably something Boris Johnson would like to avoid for now.