Ten million Americans watched the coronation of Britain's King Charles III on TV, most of them aged 55 or over.

An average of 10.3 million people in the United States tuned in for the events in London on Saturday, according to estimates from media data company Nielsen, which tracked audiences across 11 broadcast and cable television networks between 5 a.m. and 10 a.m. ET.

That's roughly 1 million fewer than the number of people who watched Queen Elizabeth II's funeral last September, and little more than a third of the 29 million who watched Prince Harry and Meghan Markle's wedding in 2018.

Polling suggests the monarchy's appeal among younger Brits is waning, and the US viewing figures suggest a similar trend. The first coronation in 70 years attracted only 360,000 American viewers in the 18-34 age group, with a further 1.6 million in the 35-54 demographic. The vast majority — just over 8 million — were 55 or older.

Across the pond, the British TV audience for Saturday's spectacle peaked at 20.4 million just after midday (7a.m. ET) when the King received his crown, according to data provided by the UK Broadcasters' Audience Research Board (Barb). The company did not provide a breakdown of audience by age group.

But the overall peak viewing figure in the United Kingdom was 9 million down on the number recorded for the Queen's funeral, according to media reports. The BBC audience for the coronation was down about 5 million from the 20 million that tuned into BBC One — the UK public broadcaster's main channel — for that service last September.

In 1953, more than 20 million people watched the late Queen being crowned, according to estimates based on surveys by the BBC at the time. Cameras were installed in Westminster Abbey for the first time to cover that coronation, which the BBC has described as the first mass television event in the UK.

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