The article covers a number of social issues in the works of British Liberal theorists of the first half of the 20th century. The author’s objective is to analyze the peculiarities of the social concepts formation and evolution in British Liberal political thought in the context of the United Kingdom’s socio-economic development in the first half of the 20th century. The article is based on the philosophical, economic and journalistic works of the dominant political figures and theorists of Liberalism of the first half of the 20th century — Maynard Keynes, David Lloyd George, Leonard Trelawny Hobhouse, etc. The basic principles of New Liberalism in the UK were formulated during the late 19th — early 20th century. But new political, social and economic factors (the low rate of economic growth and high levels of unemployment in the 1920s, the Great Depression, the Liberal party being replaced by the Labour party in the two-party system) forced the Liberals to look for new approaches to social issues. When the basic social programmes had been implemented in the UK, the Liberals put forward a concept aimed to rise the living standards of the whole population of the country. The new social programme proposed by the Liberals was based on the elements of economic regulation that meant the renunciation of the traditional Liberal principle, i.e. free economy.