The beer, called Broken Dream Breakfast Stout, is brewed near Reading in Berkshire by Siren Brewery, which was founded five years ago by brewer Darron Anley.
Speaking at Camra's Great British Beer Festival in London's Olympia, he revealed that the 6.5 per cent strength beer had some interesting ingredients, including coffee, oats and milk - hence the breakfast part of its name.
Around 2.7 million pints are brewed every year, with 20 per cent exported to 14 countries.
"It's very brave of Camra to give the top award to a stout on one of the hottest days of the year," Mr Anley said.
Judges praised the beer's "deep and complex blend of chocolate, coffee and a touch of smoke."
They commented that it stood out for its "superb" aroma, taste and finish.
Nick Boley, Camra's national director said: "This is a distinctive, strong, well-balanced stout from an outstanding craft brewery. If there is any beer in the world that is dangerously drinkable, it's this one."
Green Jack brewery based in Suffolk took second place for its barley wine Ripper (8.5% ABV), described as "dangerously smooth", with well-hopped flavours.
It was named the Champion Winter Beer of Britain earlier this year.
Tim Dunford, from Green Jack Brewery, said: "We really love our strong beers and used to travel to Belgium all the time when we first got into the industry. I fell in love with the style and we have gone on from there."
Bronze was taken by Tyne & Wear-based Mordue for their Workie Ticket (4.5% ABV), Judges said it was a "complex and tasty bitter."
Garry Fawson, from Mordue Brewery, said: "As a bitter, Workie Ticket isn't the most fashionable of beers with everything moving towards being pale, hoppy or cloudy, so we're especially pleased that it has made such a comeback."
