The United Kingdom was formed in 1801 with the Act of Union between the Kingdom of Great Britain and Ireland; the Kingdom of Great Britain itself being formed in 1707 with a similar act of Union between the Kingdom of England and the Kingdom of Scotland (Wales at the time being considered part of England). The United Kingdom of Great Britain and Northern Ireland, the latest incarnation of a British state, was formed after the Irish War of Independence, resulting in a part of Ireland referred to as Northern Ireland remaining with the United Kingdom, and the other part becoming and independent Irish country.
From 1775 to 1783, the Kingdom of Great Britain fought the newly formed United States, made up of thirteen of its North American colonies. The American rebels won the war, leading to their independence and establishment as an independent, sovereign country. The United Kingdom also fought on the side of the Allies during World War II, as one of the four leading countries of the alliance.
The relationship between the United Kingdom and Ireland in the Fallout universe are unknown, since Ireland did not officially declare itself a republic or leave the Commonwealth of Nations until 1949. It is likely however, that these events still transpired, considering that the national flag of Ireland is found multiple times in the Commonwealth. This flag, while created in 1830, did not enter common usage until Ireland became a republic in 1949 and the flag was adopted as the national flag of Ireland. The capital city of Wales is also unknown; while it is Cardiff in the real world, Cardiff did not become the Welsh capital until 1955.
Dialogue suggests that the country was ruled by a queen before the outbreak of the Great War.
No details are known about the state of the British Isles after the Great War. However, in the 23rd century, Allistair Tenpenny left the country for the Capital Wasteland in the United States to seek wealth and fortune, possibly hinting at some of the possible conditions in the post-War United Kingdom.
The United Kingdom was a member of the European Commonwealth until its dissolution in 2060. The United Kingdom quarelled with other former members of the Commonwealth over the last remaining quantities of oil on Earth, sparking a bloody conflict known as the European Civil War.
Captain John Smith was an English explorer who was the first European to discover Point Lookout in 1612. In addition, two English settler ships, the Ark and Dove, landed near Point Lookout in 1634, and began the process of the founding of Maryland.
In the Fallout 4add-onFar Harbor, one fisherman in Far Harbor, Kye, claims his family hails from Yorkshire, a group of four counties in northern England. this seems likely considering he speaks with an accent.
In Fallout Tactics, Sharon's family is claimed to stretch back to the English county of Essex. In addition, one of Martin's ancestors once ran a software company in England that ended up going out of business.
There are several characters of Irish descent from the island of Ireland in the Fallout series. It is never explicitly stated whether Ireland is part of the United Kingdom in the games' timeline, but in the Commonwealth, there is an abundance of Irish republican flags, which did not become popularly used until 1922 after Ireland broke away from the United Kingdom. Therefore, it is most likely a republic did form in this timeline.
Patrick the Celt from Fallout is descended from Americanized Celts and keeps his heritage alive by collects clothing, food, stories, songs and knowledge of Celtic history. He knows the Irish song Na Gheala Mbeadh (which is very poor Irish for "The Light Would," possibly a mistranslation of "Mo Ghile Mear," or "My Gallant Darling").
In the Fallout 3 quest Stealing Independence, Abraham Washington will erroneously refer to Fort McHenry as "Fort McHarry." James McHenry was an Irish-born military surgeon important figure in the American Revolutionary war.
Colin Moriarty speaks with a working class Dublin accent. He claims he has lived in the United States for most of his life but does not specifically state where he came from.
Dunwick's Irish Red was an Irish red ale manufactured and distilled by the Dunwik company prior to the Great War. It cannot be found in any game; however, the logo for it can be found on beer taps across the Mojave Wasteland.
In the underpass near the Nipton Road reststop there is a piece of graffiti which states "the centre cannot hold," a quote from the Irish poet WB Yeats' poem "The Second Coming."
The American Revolutionary War, and several key British figures who were active during that timeframe such as King George III, and Thomas Gage, are referenced in Fallout 3 and Fallout 4.
In Fallout 4, a Mr. Handy called Whitechapel Charlie, has a small Union Flag on his chassis. This suggests that, unlike the United States, the United Kingdom retained its real world flag prior to the Great War.
In the Fallout 76 add-on Wild Appalachia, the United Kingdom is listed as the correct answer to the question "Which country was the first to build a major railway system?" in an exam at the Pioneer Scout camp.
The Light support weapon (LSW) being featured in the Fallout universe may give some information about the United Kingdom, as the weapon was developed and issued in the mid-1980s and is past the point of Divergence.
"Allistair Tenpenny came to the Capital Wasteland from Great Britain to seek his fortune, so that alone tells you that the U.K. was also hit in the war. And if he came to U.S. to succeed, that says a lot about how screwed up Europe must be. So we just allude, a little bit, to the state of the rest of the world. We like to leave a lot to the players' imaginations, and somebody like Tenpenny serves as a catalyst for those thoughts." – Emil Pagliarulo
James, the Lone Wanderer's father, speaks with an Irish accent because The voice actor who portrays him, Irish actor Liam Neeson, used his natural speaking voice to portray him.