The Queen’s birthday celebrates the monarch of a country. Different countries celebrate on different dates and is adopted by each country by royal proclamations or statute laws.
Her Majesty the Queen's Birthday is celebrated on different dates in Commonwealth territories. Anguilla, Gibraltar, Montserrat, the Cayman Islands, and the Turks and Caicos Islands celebrate the holiday on the third Monday in June. Other Commonwealth realms and British overseas territories have chosen other dates.