Ten years ago, the United Kingdom was faced with a challenge related to issues of territorial integrity of the state. The paper analyzes the constitutional and legal practice related to holding referendums on selfdetermination of peoples in the Falkland Islands, Scotland and the referendum on the withdrawal of Great Britain from the European Union (Brexit). Comparative legal analysis of the referendums under consideration consists in comparing such criteria as: the prerequisites for a referendum on self-determination, the organizational and legal regulation of the referendum, political and legal consequences of the referendum. It is noted that the role of the institution of referendum in the constitutional and legal mechanism for the implementation of democracy in Great Britain occupies a special place. The use by the British Government of the institution of a referendum to legitimize the decisions on self-determination of the Falkland Islands, Scotland and on secession from the European Union made it possible to achieve the set goals, namely: the Falkland Islands and Scotland remained part of the United Kingdom; the exit from the European Union took place. Based on a binary analysis of the internal and external aspects of the right of peoples to self-determination, which implies taking into account international legal and domestic consequences in the event of the realization of this right, the most noticeable trends are highlighted.