Zayn Malik quits tour: One Direction's billion-dollar brand at risk as stress forces member to leave world tour

Malik, 22, has been sent home

The X Factor-created band are tipped to earn $1 billion from music (Getty Images)

He’s not the first Brit to be caught with his arm around the wrong woman in one of Thailand’s fleshpots. But Zayn Malik has placed One Direction’s mission to become the first billion-dollar boyband at risk after quitting their world tour, citing a stress diagnosis.

Malik, 22, sent the quintet’s army of Directioners into Twitter meltdown when he left his group members to film a commercial video in Hong Kong without him.

A spokesman for the band said: “Zayn has been signed off with stress and is flying back to the UK to recuperate. The band wish him well and will continue with their performances in Manila and Jakarta.”

The X Factor-created band are tipped to earn $1 billion from music, performances, endorsements and merchandise if they can only stay together long enough to cash in on their popularity peak.

The band’s fans questioned the implications for Malik’s relationship with his fiancé Perrie Edwards of Little Mix, another X Factor-created band. The pair have been engaged since 2013. “Lauren Rich is no where near as pretty as Perrie so there's not chance that Zayn would go for her,” deduced one Twitter analyst.

On Wednesday the star assured his 14.1 million Twitter followers: “I’m 22 years old ... I love a girl named Perrie Edwards. And there's a lot of jealous f***s in this world I'm sorry for what it looks like x”

That apology did not prevent Paddy Power cutting the odds on Malik leaving the band permanently from 2/1 down to 5/4 - and also offering 5/4 that Zayn and Perrie will be calling off their engagement.

One Direction are due to perform in Manila on 21 and 22 March as part of their On The Road Again tour. Malik hopes to rejoin his comrades, Harry Styles, Niall Horan, Louis Tomlinson and Liam Payne, when they continue their tour in South Africa a week later.

Boybands rarely survive the loss of a key member. Take That split shortly after Robbie Williams walked out in 1995 and it took more than a decade for the wounds to be healed with a successful reunion.

Often forged from disparate personalities, with whom they are forced to live at close quarters during an endless grind of promotional appearances, the pressure of keeping girlfriends, boyfriends and even drug use secret, adds extra pressure on boyband members, whose role is to maintain a gleaming smile as long as they are in the public eye.

Zayn Malik of One Direction (Getty Images) (Getty)

A source told The Sun: “Zayn finds it tougher than the rest of his bandmates dealing with fame. Having his every movement scrutinised causes great anxiety and the pictures which surfaced with the fan yesterday was the final straw. He did nothing wrong but the amount of criticism he received was simply too much. He needs to get away.”

Coincidentally, it was reported that the One Direction members could face fines if they are caught using or promoting illegal drugs during the concerts in the Philippines.

Malik and Tomlinson featured in a video last year in which they were shown allegedly smoking cannabis and joking about drug use.

The country’s Bureau of Immigration said the pair had been asked to post bonds of more than £3,000 each which will be forfeited if they fall foul of the regulations.