What is a mugwump? Boris Johnson's bizarre attack on Jeremy Corbyn
Mugwump was initially a native American term for a war leader
Boris Johnson has been quizzed about his description of Jeremy Corbyn as a "mutton-headed old mugwump" but what does it mean and where does it come from?
It's an insult that perhaps only Boris Johnson would use, and it appears that even he did not know exactly where it came from.
The Foreign Secretary said he had borrowed it from author Roald Dahl's children's classic Charlie And The Chocolate Factory.
In fact, the word appears not in that book but in the much-loved story-teller's 1972 follow-up, Charlie And The Great Glass Elevator, in which Willy Wonka refers to Mrs Bucket as "my dear old muddle-headed mugwump".
But Dahl himself was borrowing from earlier sources when he used the term, which has made a surprising number of appearances in popular culture with a series of entirely different meanings.
Explaining where he had found it, Mr Johnson told ITV1's Good Morning Britain: "It's a long time since I read it, but I think it's in Charlie And The Chocolate Factory.
"I think Willy Wonka says it either to the parents of Violet Beauregarde or Augustus Gloop."
In fact, mugwump was initially a native American term for a war leader, which was taken up in the 1880s to describe members of the US Republican party who switched to support Democrat presidential candidate Grover Cleveland.
For some time afterwards, the word was used in the US to describe a political turncoat. The Oxford English Dictionary defines the word as "a person who remains aloof or independent, especially from party politics."
More recently, mugwumps featured in the graphic and surrealistic 1959 novel Naked Lunch by Beat Generation writer William Burroughs - filmed by David Cronenberg in 1991 - as a bizarre and reptilian alien species.
The term also appeared in the best-selling Harry Potter series to describe members of the International Confederation of Wizards, of which the character Albus Dumbledore was appointed Supreme Mugwump.
Mugwumps even entered the UK pop charts in 1994 when they were mentioned in the chorus of Bomb The Bass hit Bug Powder Dust, a homage to the Burroughs book.
Theresa May quizzed
BBC Radio Derby's Chris Doidge asked Theresa May if she knew what a mugwump is. Her response can be heard below.
Responding to the comments during a campaign visit to Harlow in Essex, Mr Corbyn said: “We’re eight days into the election campaign and the Tories have reduced to personal name calling. I’ve never been involved in that and never will be.
“We’re in this election because we have a serious debate to be held on all the issues facing this country, such as housing, schools, health… We approach this in a responsible, serious way, I leave that kind of language to others.”
Mr Corbyn promised a country that is “properly housed”, as he unveiled research showing Labour councils have built an average of nearly 1,000 more homes since 2010 than their Tory counterparts.
“We will build a million homes over the period of a Parliament, half of which will be council and housing association for rent and be totally affordable, because that is the Labour way.”
Comedian David Baddiel weighs in
A tweet by David Baddiel has been labelled the "greatest own ever" after he compared Boris Johnson's language to fictional schoolboy Billy Bunter.
The comedian hit out at the Foreign Secretary after his description of Labour leader Jeremy Corbyn as a "mutton-headed old mugwump".
Baddiel, 52, posted on Twitter: "Nothing makes me want to vote for Corbyn more than Boris Johnson using - and thinking it's adorable - his stupid Billy Bunter language."
One user challenged him over the comparison to Charles Hamilton's obnoxious, anti-hero character, replying "you haven't read much Billy Bunter, have you @Baddiel?"
This prompted what one fan dubbed the "greatest Twitter own ever" as the television presenter responded with a photo of a newspaper clipping showing himself as a young boy surrounded by annuals in which the character appears.
Baddiel later clarified that he does not want to vote for Mr Corbyn but "Boris saying c**** stuff like that just *makes* me want to".