… or do they just dispense with it?
How old would King George Nth* have to be before he’d be allowed to speak at his own coronation? 13? 18?
*Yes, I know that Prince George may very well not take George as his Regnal Name. Just using it as an example.
I doubt there are any actual rules. When was the last time Britain had a child monarch? James VI of Scotland? Edward VI of England.
It was narrowly avoided with Victoria, who had her 18th birthday just a month before her uncle and predecessor, William IV, died. Preparations for a regency had already been made; a law, the Regency Act 1830, was adopted (and then became moot and never entered into force). That act would have required the Regent (Victoria’s mother) to take her own oath of office. It doesn’t say what would have happened to Victoria’s coronation; a possibility would have been to simply delay it until her 18th birthday. Legally, a coronation isn’t necessary to ascend to the throne anyway - that happens ipso facto upon the predecessor’s death.
Compare and contrast, as they say, with the only recent example I can think of - Wilhelmina of the Netherlands who inherited at 10, but was under the Regency of her mother until 18, when the formal inauguration and oath of office took place. Her mother took an oath of office as Regent (actually twice, once during her husband’s illness and again when he died).
The coronation ceremony in the UK doesn’t traditionally include a speech by the monarch beyond the oath-taking, though there would probably be a broadcast speech in the evening. Is the OP perhaps thinking of the State Opening of Parliament? The speech then is just the Prime Minister’s catalogue of policy priorities and legislative proposals for the year. The Regent would probably do it till the monarch is of age, or it could even be delegated to someone else altogether - I think that’s been done before.
And the monarch doesn’t even read out the coronation oath. The Archbishop of Canterbury does that and the monarch then briefly promises to obey it.
It can be delegated to counsellors of state. Essentially, they are next people of full age in line for the succession - though, occasionally, statutes interfere with that by appointing individuals as counsellors of state ad personam; Prince Philip, for instance, was one. It can also be delegated to Lords Commissioners, who are usually high-ranking politicians and members of the Church of England clergy, and this has happened during Elizabeth II’s pregnancies.
This whole question makes me wonder whether, in this day and age, they might just delay the coronation until George VII reached his majority. The Oath is pretty demanding, requiring the monarch to pledge their whole self to the service of the nation for life. Not sure that’s something we could reasonably ask of a 5 year old.
The Regency Act says:
So an underaged monarch has no oaths to take, and presumably no reason to have a coronation yet.