The Royal Titles Act 1953 (1 & 2 Eliz. 2. c. 9) is an act of the Parliament of the United Kingdom. It authorizes the monarch to alter his style and titles for the United Kingdom as well as territories whose foreign relations are under the responsibility of His Majesty's Government in the United Kingdom.
A royal proclamation was made under the act on 28 May 1953. It defined the then Queen's titles as: