The owes much to a shrewd realisation on the part of its co-founder, James Watt.

The 42-year-old, who announced his departure as chief executive on Wednesday, realised early on that punk, once a subculture, could be turned into a lucrative marketing brand.

Under Watt, and his co-founder Martin Dickie, BrewDog styled itself as an abrasive upstart on a mission to upset Big Beer and, .

Its cornerstone product was christened Punk IPA, while the crowdfunders who supplied much of its early-stage investment were given the soubriquet “Equity Punks” and invited to rowdy annual meetings that resembled rock festivals rather than an investors’ gathering.

Along the way, Watt revelled in his role as the snarling public face of , while Dickie took a back seat.

Watt gleefully lashed out at anyone who BrewDog did not consider “punk”, often as part of the company’s frequent, sometimes near-the-knuckle publicity stunts.

The Scot, who comes from a successful east coast fishing family, threw taxidermy cats out of a helicopter above the City of London, a clunky reference to the financial district’s fat cats.

He and Dickie displayed their contempt for the corporate suits of the beer world by filming themselves blowing up cans of Heineken.

The strategy worked a charm. From a tiny startup operating out of Dickie’s mum’s garage, the pair created what is now the seventh-biggest UK beer brand.

Through hard graft and canny marketing, they also helped spur interest in a wider variety of styles, such as IPAs and stouts, to the benefit of the wider “craft beer revolution”.

Yet as the company has grown, from a standing start in 2006 to revenues of £321m in 2022, Watt struggled to ride the tiger of publicity.

BrewDog’s punk clothing began to fray in 2017. First, it threatened to sue a small family-run pub in a copyright row. Watt and dropped the suit.

But he was angrily defensive about that dared to name itself Draft Punk. “They can’t own punk, that’s the whole point,” said the unfortunate bar owner at the time.

Later that year, the company announced that a , valuing the business at about £1bn.

BrewDog was beginning to look less like a punk challenger to the status quo and more like the City fat cats it had once showered with stuffed felines.

Efforts to wrest back control of the narrative, through ever more daring stunts, didn’t always go to plan.

The , a pink “beer for girls”, ostensibly to raise awareness about gender pay inequality and sexist advertising, was criticised as cynical.

A “transgender beer” raised money for LGBTQI+ charities but drew criticism from Stonewall for the language used. A “protest beer” mocking Vladimir Putin’s homophobia deployed uncomfortable tropes about homosexuality.

But BrewDog’s punk image really began to unravel in 2021, when a group of people who had worked at the brewer, under the banner “Punks with Purpose”, accused it – and Watt in particular – of fostering a “culture of fear” in which workers were bullied and “treated like objects”.

The company apologised publicly but Watt about the company, indicating in a post on the company’s web forum that their anonymity was not guaranteed.

Watt threatened to sue the BBC over claims made in the documentary, including that he had made female staff feel “uncomfortable”. BrewDog even took a complaint to the media regulator, Ofcom, which was dismissed.

One revelation that raised eyebrows was Watt’s own previous £500,000 investment in Heineken, one of the corporate behemoths he had ridiculed. Since then, BrewDog has to help it expand in the People’s Republic.

As concerns about its treatment of staff rumbled on, BrewDog , which offers certification of a company’s ethical commitment to the environment, community and employees.

Watt has committed to donating some of his shares in the company to staff and some to the Founders’ Pledge, an organisation that encourages entrepreneurs to direct some of their wealth to projects that “drive positive change”.

Yet earlier this year, BrewDog met fresh criticism when it to the accredited real living wage scheme – hiring new staff on the legal minimum instead and freezing pay for bar staff in London.

And if there were any lingering vestiges of punk around Watt, he appeared to shed them when fans of the brand spotted him attending Nigel Farage’s 60th birthday party with his partner, the former Made in Chelsea star Georgia Toffolo.

Watt’s departure as BrewDog chief executive comes as the company aims to make itself as attractive as possible to investors, before a mooted stock market float that some analysts have said could value the company at £2bn.

That could seal a bumper payday for Watt, who owns 21% of the company, proving that BrewDog’s brand of punk is particularly profitable.