In the United Kingdom, the Accession Council proclaims a new monarch upon the death of a previous monarch. Legally the accession itself will have already taken place; it is automatic under the Act of Settlement 1701.

Immediately after the death of a monarch, Privy Councillors, Members of the House of Lords, the Lord Mayor of London, the Aldermen of the City of London, High Commissioners of Commonwealth countries, and several leading citizens are summoned to meet in St James's Palace in London. The Council then makes a Proclamation of Accession, which confirms the name of the heir, and all Privy Counsellors attending sign it. The Proclamation is traditionally read in London, Edinburgh, Windsor, and York at several traditional locations. It is furthermore read at a central location in each town or village.

The new Sovereign takes an oath to preserve and defend the Church of Scotland. (Queen Elizabeth II was in Kenya when she acceeded to the throne. Thus, the Accession Council had to meet on two different days, first for the proclamation and then so that the Queen could take the oath.) The new Sovereign must also take an oath relating to the Church of England, but that is done in the presence of Parliament. This oath, known as the Accession Declaration, took the following form from its introduction in 1689 until 1910:

I, N, profess, testify, and declare, that I do believe that in the Sacrament of the Lord's Supper there is not any Transubstantiation of the elements of bread and wine into the Body and Blood of Christ at or after the consecration thereof by any person whatsoever: and that the invocation or adoration of the Virgin Mary or any other Saint, and the Sacrifice of the Mass, as they are now used in the Church of Rome, are superstitious and idolatrous. And I do solemnly in the presence of God profess, testify, and declare that I do make this declaration, and every part thereof, in the plain and ordinary sense of the words read unto me, as they are commonly understood by English Protestants, without any such dispensation from any person or authority or person whatsoever, or without thinking that I am or can be acquitted before God or man, or absolved of this declaration or any part thereof, although the Pope, or any other person or persons, or power whatsoever, should dispense with or annul the same or declare that it was null and void from the beginning.

This oath was originally required by the Test Acts to be taken by all members of either house of Parliament, and all civil and military officers. However, following Catholic Emancipation, it later came to be taken only by the King. At the time of George V's accession, the oath itself was replaced by another that was not as anti-Catholic:

I, N, do solemnly and sincerely in the presence of God, profess, testify and declare that I am a faithful Protestant, and that I will, according to the true intent of the enactments to secure the Protestant Succession to the Throne of my realm, uphold and maintain such enactments to the best of my power.