Throughout his tenure as London mayor, the hay bale style became increasingly unkempt and recognisable.

At different times described as a "straw-coloured mop", "eccentrically windblown" and resembling a "mediaeval monk", Boris Johnson's talismanic haircut has helped define a political career that has now led to Downing Street.

The messy mass of platinum blond locks has become an unmistakeable brand in an era where celebrity and politics have combined, symbolising the chaotic and gaffe-prone style that charms his supporters and appals his critics.

To his backers, the haircut mirrors his unconventional thinking and personality, which they see as an antidote to a monolithic political order that they blame for economic catastrophe and an erosion of national sovereignty.

To his opponents, it demonstrates a buffoonish temperament that is unsuited to public office, and which makes Britain a laughing stock on the international stage.

Obvious comparisons have been drawn between Johnson and US President Donald Trump, whose eccentric haircut also become intertwined with his political image.

Johnson and Trump have both ridden the populist wave to power, with the British politician integral in the country's 2016 vote to leave the European Union.

Pictures of Johnson as a child reveal the platinum blond thatch was a feature from a young age.

During his university years in the 1980s, Johnson favoured a less raggedy side parting, largely blending in with the hirsute trends of the time.

But as his political career took off, the style became ever more distinctive, long on top -- swept to one side -- and short at the back in what magazine Marie Claire called the "mediaeval monk" cut.

US chatshow host David Letterman famously asked the then mayor how long he had been cutting his own hair.

Weaponised hair

Throughout his tenure as London mayor, the hay bale style became increasingly unkempt and recognisable.

Historian Greg Jenner wrote on Twitter that by this time, Johnson had "weaponised his hair as iconic branding".

"I've seen him deliberately mess it up before giving a speech," he wrote.

Johnson famously missed out on becoming prime minister in 2016, but a neat trim in January was taken as the first sign he was girding up for another run at the top office as Theresa May's government wobbled.

Stylist Nick Mazer, who was responsible for the cut, said the result was an accident, telling The Sun that Johnson had said to him "'Don't change me'".

"I was a little nervous and cut it shorter than I should."

"He's kept that shorter style ever since and it suits him far better than his usual wild mane of hair," he said.

Others were less impressed, with Twitter users pointing out that his hair was thinning and any Samson-like powers on the wane.

"Johnson's hair feels somehow talismanic of his ego, so I can see why people want to jeer," wrote Jenner.

Johnson has also fended off suggestions he dyes his hair, claiming he was joking during a 2016 interview in which he said he did.

Asked at a recent hustings if he dyed his hair, Johnson said it was an "outrageous suggestion".