BrewDog, the Scottish craft beer business, and former winners at the Great British Entrepreneur Awards, has reached unicorn status after a private equity firm buys into the company. It seems that its success lies with its customers becoming its evangelisers.

In the digital era being close to your customer matters, but BrewDog has taken this relationship to its extreme.

With BrewDog its customers are also investors and many of them have become sort of competitors. But that’s okay, what the company has done is create a fan base, an army of supporters who go out and preach its virtues to the rest of the world.

The company, which raised £50 million from 50,000 shareholders, then tapped the crowdsourced lending market, with the issue of a bond providing investors with a 7.5 per cent annual interest rate, has seen its value pass £1 billion after US private equity outfit TSG spent £213 million acquiring 22 per cent of the company.

Of that £213 million, £100 million will be for new shares, and provide the business with extra capital, £113 million on buying existing stock. The £113 million will be split between the two founders, James Watt and Martin Dickie, and the company’s investors.

Smaller investors, referred to as ‘equity punks’ will be able to sell up to 15 per cent of their stock, but capped at 40 shares each.

The investment means that shares bought in 2010 as part of the so called ‘Equity for Punks 1st round’, are valued at no less than 2,765 per cent of the price at the time they were issued. Investors who climbed aboard in April 2016 will see a 177 per cent return.

It’s good day for the company’s founders and backers, but how did they do it?

Having beers with a good taste helped.

But the company has also managed to engage its fans in a way that has turned them into a kind of sales force.

Not only has it secured investment from people who like its beers, it has put the recipes for its beers online – a move that truly endeared it to its public.

It was a clever move, although actually not quite as radical as it may seem. It has put the recipes of its beers into the public domain – helping to reinforce its ‘beer of the people’ (or punk) image but has not really cannibalised its product, as some might have thought, because the key ingredients – brand, distribution and ability to scale-up – are not transferable.

But BrewDog has deliberately and quite cleverly cultivated this ‘punk’ image. But, now that it has linked up with private equity, can it maintain this image? Punk goes mainstream – it always has. Johnny Rotten still rebels, but these days it feels more like middle class rebellion.

Can BrewDog, which is hoping that with TSG’s support it can go public, hang on to punk image?