The social structure of the United Kingdom has historically been highly influenced by the concept of social class, with the concept still affecting British society in the early-21st century.
British society, like its European neighbours and most societies in world history, was traditionally (before the Industrial Revolution) divided hierarchically within a system that involved the hereditary transmission of occupation, social status and political influence. Since the advent of industrialisation, this system has been in a constant state of revision, and new factors other than birth (for example, education) are now a greater part of creating identity in Britain.
Although definitions of social class in the United Kingdom vary and are highly controversial, most are influenced by factors of wealth, occupation and education. Until recently the Parliament of the United Kingdom was organised on a class basis, with the House of Lords representing the hereditary upper class and the House of Commons representing everyone else. The British monarch is usually viewed as being at the top of the social class structure.
British society has experienced significant change since the Second World War, including an expansion of higher education and home-ownership, a shift towards a services-dominated economy, mass immigration, a changing role for women and a more individualistic culture, and these changes have had a considerable impact on the social landscape. However, claims that the UK has become a classless society have frequently been met with scepticism. Research has shown that social status in the United Kingdom is influenced by, although separate from, social class.
The biggest current study of social class in the United Kingdom is the Great British Class Survey.
Prior to the eighteenth century, one did not speak of class or classes. Older terms like estates, rank, and orders were predominant. This change in terminology corresponded to a general decrease in significance ascribed to hereditary characteristics, and increase in the significance of wealth and income as indicators of position in the social hierarchy.
The "class system" in the United Kingdom is widely studied in academia but no definition of the word class is universally agreed to. Some scholars may adopt the Marxist view of class where persons are classified by their relationship to means of production, as owners or as workers, which is the most important factor in that person's social rank. Alternatively, Max Weber developed a three-component theory of stratification under which "a person’s power can be shown in the social order through their status, in the economic order through their class, and in the political order through their party. Besides these academic models, there are myriad popular explanations of class in Britain. In the work Class, Jilly Cooper quotes a shopkeeper on the subject of bacon: "When a woman asks for back I call her 'madam'; when she asks for streaky I call her 'dear'."