On Saturday, Britain will witness its first coronation in 70 years, as Charles III is crowned king in an elaborate Christian ceremony steeped in solemn ritual and more than a millennium of history.

The coronation, which is the religious confirmation of his accession after the death of his mother, Queen Elizabeth II, last September, is the first of a British king since 1937.

Prime Minister Rishi Sunak called the event "a moment of enormous national pride" and "a demonstration of our country's character."

However, not everyone is in a celebratory mood. Republican opponents who want an elected head of state plan to protest on the day with signs declaring "not my king."

Anti-monarchist activist group Republic plans to hold a demonstration a short walk from where the king is due to be crowned, though they received letters from the Home Office warning them about new powers handed to police to deal with public demonstrations.

"Republic will not be deterred, and we will be protesting on Trafalgar Square and along the route of the coronation procession on Saturday," the group's chief executive, Graham Smith, told The Guardian.

The annual British Attitudes Survey also uncovered a shift in attitudes towards the royals. Of the respondents, 29 percent said the monarchy was "very important," 26 percent thought it was "quite important," 20 percent said it was "not very important," and 25 percent said it was "not at all important/abolish."

The number of people who said that the monarchy is "very important" has never been lower since data collection began in 1983. There was also a clear difference in attitudes between older and younger generations. Just 12 percent of 18- to 34-year-olds view the monarchy as "very important," compared to 42 percent of the 55+ age group.

Further afield, Charles's position looks increasingly tenuous as the hereditary monarch in 14 Commonwealth countries outside the UK.

Australia, Belize, and Jamaica are already indicating moves towards becoming republics while Charles is also facing calls to apologize for his ancestors' involvement in colonialism and the slave trade.

"Interest in British royalty has waned since more Jamaicans are waking to the reality that the survivors of colonialism and the holocaust of slavery are yet to receive reparatory justice," said the Reverend Sean Major-Campbell, an Anglican priest in the Jamaican capital, Kingston.

The coronation is "only relevant insofar as it kicks us in the face with the reality that our head of state is simply so by virtue of biology," Major-Campbell added.

(With input from agencies)