defined difference between an ordinary and a best bitter other than one particular brewery's best bitter will usually be stronger than its ordinary. Two groups of drinkers may mark differently the point at which a best bitter then becomes a premium bitter. Hop levels will vary within each sub group, though there is a tendency for the hops in the session bitter group to be more noticeable. Bitter is dispensed in most formats — hand-pulled from the cask, on draught from the keg, smoothflow or bottled. Drinkers tend to loosely group the beers into: Session or ordinary bitter have strength up to 4.1 per cent ABV. The majority of English beers with the name IPA will be found in this group, such as Greene King IPA, Flowers IPA, Wadworth Henrys Original IPA, etc. These session bitters are not as strong and hoppy as the 18th and 19th century IPAs (or as an India Pale Ale would be in the USA) although IPAs with modest gravities (below 1.040) have been brewed in England since at least the 1920s. This is the most common strength of bitter sold in English pubs, accounting for 16.9 per cent of pub sales. Best bitter have strength between 3.8 per cent and 4.7 per cent ABV. In the United Kingdom, Bitter above 4.2 per cent ABV accounts for just 2.9 per cent of pub sales. The disappearance of weaker bitters from some brewer's rosters means "best" bitter is actually the weakest in the range. Premium bitter have strength of 4.8 per cent ABV and over. Also known as extra special bitter, for instance Fuller's ESB. Golden ale or summer ales were developed in the late 20th century by breweries to compete with the pale lager market. A typical golden ale has an appearance and profile similar to that of a pale lager. Malt character is subdued and the hop profile ranges from spicy to citrus; common hop additions include Styrian Golding and Cascade. Alcohol is in the 4% to 5% range ABV. The style was marketed in 1989 by John Gilbert, a former brewer at Watney in Mortlake, London, who had opened his own operation, the Hop Back Brewery, in Salisbury, England. His aim was to develop a pale ale that could be as refreshing as lager. The result was a drier and hoppier pale ale he called "Summer Lightning", after a novel by PG Wodehouse;