Great Britain was the official name of the Kingdom of Great Britain (1707-05-01 to 1800-12-31) and consisted of the Kingdoms of England (which included Wales) and Scottland. Thus the whole island of Great Britain formed one Kingdom.
With the Act of Union (Ireland) 1800, the kingdoms of Great Britain and Ireland were united into one kingdom.
That it be first article of the union of the kingdoms of Great Britain and Ireland, that the said kingdoms of Great Britain and Ireland shall, upon the first day of January, which shall be in the year of our lord one thousand eight hundred and one, and for ever, be united into one kingdom, by the name of “the united kingdom of Great Britain and Ireland,” and ... shall be such as his Majesty by his royal proclamation under the great seal of the united kingdom shall be pleased to appoint.
Since the names of countries, nationalities, and languages are proper nouns, the consistent use of united kingdom (and not United Kingdom) within the act implies that the term was not intended to be used as an official short name.
International treaties, signed afterwords, still used Great Britain in the same way as France was used for the French Republic (i.e. in a geographical sense).
- Final Act of the Congress of Vienna (1815-06-09)
- His Majesty the King of the United Kingdom of Great Britain and Ireland:
- ART. XVII. Austria, Russia, Great Britain, and France, guarantee, ...
- and the Kings of Great Britain and Prussia,
- International Convention With respect to the Circulation of Motor Vehicles, signed at Paris, the 11th October 1909
- His Majesty the King of the United Kingdom of Great Britain and Ireland and of the British Dominions beyond the Seas, Emperor of India;
- For Great Britain :
- Great Britain and Ireland, GB;
- League of Nations Passport Conference, Geneva, 1926-05-18
- Mr. Haldane PORTER (Great Britain) said that, when a foreigner had to register with police in the United Kingdom, ...
Here it becomes apparent that a different terminology is being used depending from where it is being use (inside or outside of the United Kingdom).
Treason Felony Act 1848
If any person whatsoever shall, within the United Kingdom or without, compass, imagine, invent, devise, or intend to deprive or depose our Most Gracious Lady the Queen, from the style, honour, or royal name of the imperial crown of the United Kingdom, or of any other of her Majesty’s dominions and countries, or to levy war against her Majesty, within any part of the United Kingdom, ...
The question arises why, if parlament uses United Kingdom (since at least 1848) why is Great Britain then used in the Motor Vehicles convention of 1909 where the GB car shield was introduced?
It would seem that, for whatever reason, the British goverment preferred that Great Britain should be used in an international context.
It may be that the British goverment thought having the word 'Britain' in the name was better, while inside Britain the term United Kingdom was commonly used.
The regulation page of this passport, issued 1935, would support this view:
When did it actually disappear from the international naming conventions?
ISO 3166-2:GB is the entry for the United Kingdom of Great Britain and Northern Ireland in ISO 3166-2.
- UK was exceptionally reserved on request of the United Kingdom lest UK be used for any other country in 1974. Its main usage is the .uk internet ccTLD.
.gb is a reserved Internet country code top-level domain (ccTLD) for the United Kingdom, derived from Great Britain.
The domain was introduced with RFC 920 in October 1984 that set out the creation of ccTLD generally using country codes derived from the corresponding two-letter code in the ISO 3166-1 list. However, the .uk domain had been created separately a few months before the compilation of this list [1985-07-24]. Consequently, .gb was never widely used. It is no longer possible to register under this domain.
As far as the vehicle distinguishing sign is concerned, the replacement of "GB" with "UK" came into effect on 2021-09-28.
Convention on Road Traffic Vienna, 8 November 1968: UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND: NOTIFICATION UNDER ARTICLE 45 (4). (PDF)
The Secretary-General of the United Nations, acting in his capacity as depositary, communicates the following:
On 28 June 2021, the Secretary-General received from the Government of the United Kingdom of Great Britain and Northern Ireland, in accordance with Article 45 (4) and Annex 3 of the Convention, a notification stating that the United Kingdom is changing the distinguishing sign that it had previously selected for display in international traffic on vehicles registered in the United Kingdom, from “GB” to “UK”, and that “this change will apply only to the United Kingdom of Great Britain and Northern Ireland, and will not extend to any territories for the international relations of which the United Kingdom is responsible”.
The change in the United Kingdom’s distinguishing sign will take effect three months after the deposit of this notification, i.e., on 28 September 2021, in accordance with Article 54 (4) of the Convention.