Four years ago, James Watt spent two exhausting months on a North Sea trawler, catching herring to make ends meet.

Today he is excitedly looking forward to his own TV show, airing next month in the US.

The transformation is all thanks to the rapid growth of BrewDog, the award-winning brewer he co-founded in 2007 during breaks from fishing.

But while some self-made men forge their rags-to-riches story on the back of 6am jogs and wheatgrass smoothies, Watt has done it all while swigging from a bottle of beer.

That’s par for the course at BrewDog, which has embraced a ‘punk’ ethos by gleefully cheeking the industry’s big players.

‘Too many people think beer begins with Carling and Stella,’ laments the 31-year-old ‘Captain’ of BrewDog, a name inspired by Watt’s sadly deceased chocolate labrador Sweep. ‘They don’t care what they’re making. We want to put flavour and integrity and passion back into people’s glasses.’

His assault on ‘big beer’ has even taken physical form. ‘We went clay-pigeon shooting with cans of Tennent’s, ten-pin bowling with bottles of Budweiser and played golf with cans of Stella . . . that was good fun.’