George Galloway has explained to a caller on his show the experience of defying a three-line party whip.
Our presenter, who spent years on the Labour backbenches, was speaking after 47 Labour MPs defied Jeremy Corbyn's order to back the bill to trigger Article 50 in its first Commons vote.
Corbyn has now ordered a new three-line whip for the final vote on the bill.
While speaking to caller Steven, our presenter revealed he was never scared to defy the party line, but others weren't always so bold.
He said: "It’s petrifying for most MPs, never for me. I broke many three-line whips on issues like war or university fees introduction.
"Unless you have permission to be absent, you must be present and you must vote for the party’s line, the party’s motion, or amendment.
"If you don’t, then a disciplinary process will begin. It’s quite serious, you only do it if you have no ambition, principle is more important to you or because your conscience dictates it.
"I’m not easily frightened, but for most ambitious MPs, it’s a very big step indeed to break that whip."