Introduction. The article examines the British policy pursued in the 16th – first half of the 20th centuries in relation to the autochthonous languages of Wales, Scotland and Northern Ireland. The author characterizes the language policy of Great Britain in this period as a policy of linguistic nationalism of the English language and discrimination against the national languages of other peoples. The article also discusses the main legal acts aimed at expanding the use of the Welsh language and consolidating the status of the Welsh language as the national language of Wales.Materials and methods. To achieve this goal, the article used the method of the structural-functional approach, as well as modern principles of scientific knowledge of complex social phenomena and processes, based on a combination of macro- and microsociological research. The materials of the article were the works of scientists on the stated issues.Results of the study. It is concluded that the Welsh language has managed to maintain its independence to a greater extent than other autochthonous languages of the peoples of Great Britain, and in modern conditions there is a tendency to increase the number of people using the Welsh language in everyday life. The main findings of this article were the demonstration of specific discriminatory measures applied by the UK in relation to the Welsh language, including the ban on the use of Welsh as the language of legislation, the language of judicial proceedings and restrictions on teaching in Welsh.Discussion and conclusion. The study identifies the reasons and constitutional and legal factors for the transition from a policy of language discrimination to a policy of dialogue of cultures, as well as the influence of public figures advocating the preservation and expansion of the use of the Welsh language on the language policy of Great Britain. The constitutional significance of the Welsh Language Regulations 2011 is stated, and for the first time in the Russian-language doctrine the content of this law is analyzed.