UK Foreign Secretary Boris Johnson has levelled a memorable snipe at Opposition Leader Jeremy Corbyn, brandishing him a "mutton-headed old mugwump".

Johnson made the colourful claim in an opinion piece for The Sun newspaper today (27 April).

The member for Uxbridge and South Ruislip warned readers against regarding Corbyn as an "essentially benign Islingtonian herbivore".

In a blistering article that confirmed the Tories' election strategy to undermine Labour by attacking its leader, Johnson claimed that a Corbyn administration would be a threat to the the peace and prosperity of the UK.

"The biggest risk with Jeremy Corbyn is that people just don't get what a threat he really is," Johnson wrote.

He continued: "They look at him floundering away in the Commons and they say to themselves: Nah – that guy? PM? That's never going to happen.

"They watch his meandering and nonsensical questions and they feel a terrible twinge of human compassion. Well, they say to themselves: he may be a mutton-headed old mugwump, but he is probably harmless.

"Do you have those feelings? Have you ever thought the leader of the Opposition is an essentially benign Islingtonian herbivore? Have you felt a pang of sympathy for his plight? If so, fight it."

A mugwump is noun, of North American origin, that refers to people who do not engage in party politics.

mugwump definition
Mugwump is a North American noun. Google / screengrab

Johnson may have used the word to draw attention to Corbyn's lack of support with in the Parliamentary Labour Party and his perceived disconnect with traditional Labour voters.

Today (27 April) The Times reported that Johnson would be rolled out as the Conservative's TV and radio poster boy in the run-up to the 8 June election.

Johnson's decision to throw his weight behind the Leave campaign was seen as a huge moment in the build-up to Britain's 2016 referendum on EU membership.

Johnson made the comments in a comment piece for The Sun newspaper