The Tory chief whip Andrew Mitchell has flatly denied calling Downing Street police officers "plebs". But does anyone really use this term any more?
In the popular imagination, the word pleb evokes images of the public school boy putting down his social inferiors.
But where does the word come from?
In the very earliest days of Rome, plebeians were any tribe without advisers to the King. In time, the word - which is related to the Greek word for crowd, plethos - came to mean the common people.
But it's wrong to think of the plebeians as being the lowest of the low. During the Roman Republic, they had a set of rights, and a measure of political clout, which could make them a powerful lobby group.
Roman leaders were generally drawn from the aristocracy, but ambitious politicians could still rise to power by appealing to the plebs.
Inevitably, the word picked up an abusive taint. "If you wanted to insult the common people, you could call them plebs," says Peter Jones, who writes a weekly column on classics for the Spectator magazine. "But it wasn't the worst thing you could call them."
The renowned orator Cicero went one step further. "He called the plebs the scrapings of Romulus," says Jones.
So how did this word jump into the modern world?
Ian Brookes, consultant editor at Collins Language, says that English public schools of the 18th and 19th Centuries deliberately modelled themselves on ancient Greece and Rome.
"In public school parlance, a pleb was a pupil who was not a member of the landed classes."
As these public schoolboys left school to run the British Empire, it seems they took the word with them to describe the lower orders.
An 1832 edition of the Times uses the word during an election report from Norwich:
"The new candidate has been indulging the plebs with boundless ovations (sic) of strong drink… Quarrels and riots followed."
It also appears in Gilbert and Sullivan's 1882 opera Iolanthe, where a chorus of peers (of course) complain that "Distinction ebbs before a herd of vulgar plebs."
But one man's insult is another's badge of pride. The Plebs' League was a workers' educational organisation, active in Britain in the early 20th Century, which had ties to the Communist Party.
Ian Brookes says that these days, the word is mostly used by somebody about themselves as a mark of false modesty, such as, "I'm such a pleb when it comes to modern art."
It's rarer to hear "pleb" used as an insult, although Gordon Ramsay used it to put down rival restaurateur Sir Terence Conran in 2003: "I think he is a pleb… I would rather have food at my four-year-old daughter's prep school than eat at Quaglino's."
Ian Brookes says, "It's similar to some sex- or race-based insults, where it's OK to use it of oneself, but certainly not OK to use it of someone else."
It's not the first time the government's been accused of alluding to the word.
Last year, an agency released a newsletter highlighting the problem of what it described as People Lacking Everyday Basic Skills.
Once people latched on to the full import of the acronym, there was trouble.