Porter was a London style that turned the brewing industry upside down early in the 18th century. It was a dark brown beer – 19th-century versions became jet black – that was originally a blend of brown ale, pale ale and ‘stale’ or well-matured ale. It acquired the name Porter as a result of its popularity among London’s street-market workers. At the time, a generic term for the strongest or stoutest beer in a brewery was stout.
The strongest versions of Porter were known as Stout Porter, reduced over the years to simply Stout. Such vast quantities of Porter and Stout flooded into Ireland from London and Bristol that a Dublin brewer named Arthur Guinness decided to fashion his own interpretation of the style. The beers were strong – 6% for Porter, 7% or 8% for Stout. Guinness in Dublin blended some unmalted roasted barley and in so doing produced a style known as Dry Irish Stout. Restrictions on making roasted malts in Britain during World War One led to the demise of Porter and Stout and left the market to the Irish.
In recent years, smaller craft brewers in Britain have rekindled an interest in the style, though in keeping with modern drinking habits, strengths have been reduced. Look for profound dark and roasted malt character with raisin and sultana fruit, espresso or cappuccino coffee, liquorice and molasses, all underscored by hefty hop bitterness.
Porters are complex in flavour, range from 4% to 6.5% and are typically black or dark brown; the darkness comes from the use of dark malts unlike stouts which use roasted malted barley. Stouts can be dry or sweet and range from 4% to 8% ABV.Information from www.camra.org.uk/page.php?id=231