Since then, the date of the king or queen's birthday has been determined throughout the British Empire and, later, the Commonwealth of Nations, either by royal proclamations issued by the sovereign or viceroy, or by statute laws passed by the local parliament.

The date of the celebration today varies as adopted by each country and is generally set around the end of May or start of June, to coincide with a higher probability of fine weather in the Northern Hemisphere for outdoor ceremonies.

Most Australian states and territories observe the King's Birthday on the second Monday in June, except in Western Australia and Queensland.

Some regional areas of Western Australia celebrate the King's Birthday public holiday on alternative days for locally significant dates or events.

[7] The day has been celebrated since 1788, when Governor Arthur Phillip declared a holiday to mark the birthday of the king of Great Britain.

The annual muster of the militia was held on the King's birthday, in the most central or most convenient place in each district, and every able-bodied man between the ages of 18 and 60, aside from Quakers, Mennonites, and other pacifist sects, was to take part.

The drill ended with three cheers for the King before the participants were free to mingle about; they were known to engage in horseshoe pitching contests, wrestling matches, and settling old scores by fights before, in the summer night, the settlers and their families visited the houses of their neighbours or patronised the taverns; for the latter, it was their most profitable day all year.

For the officers, a dinner was held, during which toasts were made to the King, the Duke of York (the Commander-in-Chief), the Army and Navy, and the ladies.

[15] It was in 1845 that the Parliament of the Province of Canada passed a statute to authorise the recognition of Queen Victoria's birthday, 24 May, as a public holiday.

[16][17] After Victoria died in 1901, 24 May became Victoria Day[17] and the official date in Canada of the reigning monarch's birthday changed through various royal proclamations: for Edward VII, it continued by yearly proclamation to be observed on 24 May, but, was 3 June for George V and 23 June for Edward VIII (their actual birthdays).

However, the Prime Minister at the time, William Lyon Mackenzie King, the rest of Cabinet, and the Lord Tweedsmuir, the Governor General, felt otherwise, seeing such a celebration as a way to begin George's reign on a positive note.

Though the media mention only Victoria Day and the public are therefore almost totally unaware of the existence of the official birthday, the sovereign's official birthday is marked by the firing of an artillery salute in the national and provincial capitals and the flying of the Royal Union Flag on buildings belonging to the federal Crown, if there is a second flag pole available.

[27][28] The second time was when Queen Elizabeth II was in Canada from 17 to 25 May 2005, to mark the centennial of the entries of Saskatchewan and Alberta into Confederation; no government-initiated events, aside from those dictated by normal protocol, were organised to acknowledge the official birthday.

Charles III, who was Prince of Wales and heir apparent to the throne at the time, and his wife, Camilla, in 2012 attended events in Saint John, New Brunswick, and Toronto, Ontario, marking the Queen's official birthday.

Although that act makes reference to "Her Majesty Queen Elizabeth the Second",[35] it was still in place in 2023, the first time that New Zealand observed the King's Birthday for Charles III.

[52][53] Tuvaluans celebrate it with church services and prayers, singing "God Save the King" and "Tuvalu mo te Atua", flag hoisting, public speeches, a Royal Salute, and a parade.

[65] The King's official birthday is a public holiday in most British Overseas Territories (those parts of Britain's sovereign territory that lie outside the archipelago of the British Isles), including Anguilla, the Cayman Islands, Gibraltar, Montserrat, Saint Helena, Ascension and Tristan da Cunha and the Turks and Caicos Islands, and the Crown Dependencies (which are not parts of Britain's sovereign territory, but are dependencies of the British Crown), including Guernsey and Jersey in the Channel Islands, and the Isle of Man.

[66] Bermuda formerly marked the occasion with a public holiday but in 2008 the Progressive Labour Party government of the territory decided the day would be, beginning the following year, replaced by National Heroes' Day,[67] despite protests from some residents of the island, who signed a petition calling for retention of The Queen's Official Birthday.

[73] The Falkland Islands celebrate the actual day of King Charles III's birth, 14 November, as a public holiday.