gravity of their beer to 1.030. In order to be able to produce some stronger beer – which was exempt from price controls and thus more profitable – mild was reduced to 1.025 or lower. English breweries continued to brew a range of bottled, and sometimes draught, stouts until the Second World War and beyond. They were considerably weaker than the pre-war versions (down from 1.055–1.060 to 1.040–1.042) and around the strength that porter had been in 1914. The drinking of porter, with its strength slot now occupied by single stout, steadily declined, and production ceased in the early 1950s. However, Irish-brewed stouts, particularly Guinness, remained firmly popular. In the early 20th century, serving draught beer from pressurised containers began. Artificial carbonation was introduced in the United Kingdom in 1936, with Watney's experimental pasteurised beer Red Barrel, although this method of serving beer did not take hold in the UK until the late 1960s. 1950 to 1999: Megabreweries and microbreweries In 1960 almost 40 per cent of beer drunk nationally was sold in bottled form, although the figure was 60 per cent in the south of England, falling to 20 per cent in the North of England. Pale ale had replaced mild as the beer of choice for the majority of drinkers. Home brewing without a licence was legalised in 1963, and was to become a fairly popular hobby, with homebrewing equipment shops on many high streets. Lager rapidly rose in popularity from the 1970s, increasing from only 2 per centof the market in 1965 to 20 per cent in 1975, with English brewers producing their own brands or brewing under licence. Canned beer was also introduced about this time. A consumer organisation, the Campaign for Real Ale (CAMRA), was founded in 1971 to protect unpressurised beer. The group devised the term real ale to differentiate between beer served from the cask and beer served under pressure and to differentiate both from lager. "Ale" now meant a top-fermented beer, not an unhopped beer. CAMRA was to become an influential force, with a membership of over 170,000. At the time, brewing was dominated by the "big six" breweries: Whitbread, Scottish and Newcastle, Bass Charrington, Allied Breweries, Courage Imperial and Watneys. There were also dozens of regional breweries, although the number was dwindling as a result of takeovers, and the microbrewery sector consisted of just four long-standing brewpubs. Most pubs were owned