Unparliamentary language breaks the rules of politeness in the House of Commons Chamber, with part of the speaker’s role being to ensure that MPs do not accuse each other of lying or being drunk. Swearing, personal insults and mentions of “crooked deals” are all on the list of not-to-mention’s as well.

In a 2013 Real Business article, Erskine May was quoted as having said that “good temper and moderation are the characteristics of parliamentary language”.

In his guide to “Parliamentary Procedure”, he penned a list of profane words, which now includes: blackguard, coward, hooligan, hypocrite, idiot, git, ignoramus, liar, pipsqueak, rat, swine, stoolpigeon, sod and tart (a great deal attributable to Dennis Skinner).

For example, an MP must never accuse another of being drunk. In 1987, Labour MP Frank Cook was forced to withdraw his jibe, replacing it with “half sober”.

Read also: Strange laws from Parliament that are still applicable today

According to legend, British prime minister Benjamin Disraeli was told off by the commons speaker for declaring that half of the cabinet were “asses”.

“I withdraw it,” he said. “Half the cabinet are not asses.”

It’s also considered unparliamentary to accuse another honourable member of lying, even if they are. Winston Churchill famously used the phrase “terminological inexactitude” to get around this rule.

The way in which MPs speak was once again brought to the forefront as John McDonnell was named as Jeremy Corbyn’s shadow chancellor – and the internet has been awash with the colourful language he used on previous occasions. We rounded up some of the “finest” examples.

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Most famously, when Esther McVey was a minister in the department for Work and Pensions, McDonnell refused to apologise for quoting a constituent who called for her to be lynched during a meeting in her constituency.

Following a complaint to Labour’s leadership he later told the commons: “The substance of the matter is there is nothing to apologise for and I hope the electorate on May 7 will remove the stain of inhumanity.”

During a short-lived campaign to become Labour leader in 2010, McDonnell said that he would like to “go back to the 1980s and assassinate Thatcher”. Of course, Corbyn tried to defend McDonnell by saying many still felt “raw” about Thatcher’s years as prime minister.

Earlier in 2015, he lashed out at the conservatives’ welfare bill, and said he would “swim through vomit” to oppose the cuts. He also lists among his interests in Who’s Who “generally fermenting the overthrow of capitalism”.

And let’s not forget the time he controversially praised the IRA at a commemoration for the hunger striker Bobby Sands in London.

He said: “It’s about time we started honouring those people involved in the armed struggle. It was the bombs and bullets and sacrifice made by the likes of Bobby Sands that brought Britain to the negotiating table. The peace we have now is due to the action of the IRA.”

He then defended his comments: “The deaths of innocent civilians in IRA attacks is a real tragedy, but it was as a result of British occupation in Ireland. Because of the bravery of the IRA and people like Bobby Sands we now have a peace process.”

Furthermore, he was suspended briefly in 2009 after he picked up the ceremonial mace – a symbol of authority which is placed on the table in front of the speaker when the commons is sitting – while debating a third runway at Heathrow.

Referring to the plans of building a third runway at Heathrow, McDonnell said: “It’s a disgrace to the democracy of this country,” and then put the mace down on an empty bench.

The then deputy speaker promptly ordered McDonnell to leave.

By Shané Schutte