King Charles thanks UK for 'greatest coronation gift'

King Charles III thanked the British people for "the greatest possible coronation gift" on Monday as three days of celebrations for the historic event drew to a close with a massive volunteering drive.

"To know that we have your support and encouragement, and to witness your kindness expressed in so many different ways, has been the greatest possible coronation gift," Charles said in a written message.

After the pomp and majesty of Saturday's service, and the concert and street party fun of Sunday, Britons were urged to join in the "Big Help Out", billed as a lasting volunteering legacy to mark Charles's crowning.

The coalition of volunteer and faith groups organising the initiative hope that hundreds of thousands of people will join in, with more than 1,500 charities involved.

Charles's son and heir Prince William was due to take part in a puppy class at the Guide Dogs for the Blind Association Training Centre as part of the volunteer programme.

Meanwhile, William's children George, Charlotte and Louis got busy on a building site, renovating a scout hut in Slough, west of London.

The king was the guest of honour at Sunday's star-studded Coronation Concert, watched by 20,000 people at Windsor Castle and millions more across Britain and around the world.

Charles, 74, and Queen Camilla, 75, watched on from a royal box in the grounds of the castle west of London, as Lionel Richie, Katy Perry and the British band Take That topped the bill of performers.

Screens erected nationwide broadcast the televised event -- featuring a 70-piece orchestra, choirs and several unique dramatic performances -- to communities, while organisers said it would also be seen in more than 100 countries.

Amid the music and video message tributes from an array of public figures, Prince William took to the stage to pay tribute to his father the day after Charles was formally crowned king.

William said his late grandmother, Queen Elizabeth II, was "up there, fondly keeping an eye on us", adding she would be "a very proud mother".

"For over 50 years, in every corner of the UK, across the Commonwealth and around the world, he has dedicated himself to serve others, both current and future generations," he said.

"Pa, we are all so proud of you."

Charles's coronation on Saturday as monarch of the United Kingdom and 14 Commonwealth countries was the first in Britain in seven decades.

The glittering Westminster Abbey ceremony, steeped in 1,000 years of tradition and ritual, was attended by global royalty and world leaders as well as hundreds of UK community and charity representatives.

Thanking all those involved, Buckingham Palace said Charles and Camilla had been "deeply touched" by it.

However, there has been criticism over the arrest of republican supporters before Saturday's ceremony, with London's Metropolitan Police on Monday saying they "regretted" that six detained protesters were unable to join a rally on coronation day.

Graham Smith, chief executive of campaign group Republic, was one of those detained, and told the BBC on Sunday that "the whole thing was a deliberate attempt to disrupt and diminish our protest."

Prime Minister Rishi Sunak said Monday that officers acted based on "what they think is best" after claims politicians encouraged the crackdown.

Monday was declared a public holiday to mark the final day of celebrations -- meaning people could enjoy Sunday unencumbered.

Earlier Sunday, partygoers had flocked to tens of thousands of street celebrations and "Big Lunch" events looking to bring modern Britain's communities closer.

The evening also featured "Lighting up the Nation", in which well-known locations across Britain were illuminated using projections, lasers and drone displays.