Flag Porter. Researched and devised by Dr Keith Thomas at the Brewers’ Laboratory (Brewlab) in London, Flag Porter is a historical recreation of a porter beer from the 19th century. In 1988 deep-sea divers from the City of London Polytechnic were investigating the wreck of a ship that had sunk in the English Channel in 1825. The divers found bottles of porter onboard the wreck, brought several to the surface, and gave them to Dr Thomas, who found that although the beer had been contaminated by seawater and was undrinkable, some original yeast was still alive inside the bottles. He was able to isolate a few living yeast cells from one bottle and culture them in his laboratory until he had a sufficient amount of yeast to make a batch of beer. The first brew took place in 1988 at the Pitfield Brewery in Hoxton, London, since when the beer has been brewed regularly, mostly for sale in the United States.

Thomas contacted Whitbread, a major brewing group that had been at the heart of the porter and stout revolutions of the 18th and 19th centuries. See whitbread brewery. Whitbread supplied him with a recipe for porter from the 1850s, brewed at its former Chiswell Street brewery in the historic Barbican area of London. The recipe for Flag Porter, devised by Thomas, was based on the Whitbread recipe and used pale, brown, crystal, and black malts and was hopped with just one variety, Fuggles. See fuggle (hop). One of the many interesting facts discovered in the Whitbread archive was that the brewery was still using wood-kilned brown malt as late as 1850, at a time when pale ale brewers had switched to malt kilned with coke.

The beer that Thomas created had a second surprise: It was not jet black but dark ruby red in color. He suspects the original may have been even paler.

Despite Thomas’ best attempts, such recreations cannot be entirely accurate from a historical perspective. Amber malt, a type no longer produced (and now imperfectly understood), is replaced by crystal malt in the Flag Porter recipe, and the Fuggle hop had not yet been bred in 1825. Bitterness could not be scientifically measured in those days, so Flag Porter’s bitterness of 35 IBU is an approximation. That said, the beer is widely felt to provide a window into brewing history. The aromatics are complex, showing tangy, slightly smoky, and nutty notes underpinned by spicy Fuggle hops. The palate is fruity and rich, with notes of bitter chocolate and an intensely dry herbal finish.

Flag Porter was first brewed commercially by a London brewery, then moved to Elgood’s in Cambridgeshire before finding its current home at the Darwin Brewery in Sunderland, northeast England. The Darwin Brewery developed initially as a training unit to support the Brewlab brewing school at the local university.

See also porter.