From traditional robes to statement headpieces, royals and guests wore an array of colourful outfits for the coronation of Britain's King Charles III on Saturday, filling London's Westminster Abbey with a mix of hues and designs.

The monarch arrived in the crimson velvet Robe of State, worn by his grandfather King George VI at his 1937 coronation, a crimson coronation tunic and cream silk overshirt with royal naval trousers.

He changed into ceremonial regalia worn by his predecessors to be crowned: the gold-silk full-length Supertunica coat and the Coronation Sword Belt, and over that the gold cloth Imperial Mantle, originally made for the coronation of George IV in 1821 and the oldest vestment in the service.

A white leather glove embroidered with gilt metal thread was placed onto his right hand.

Charles was crowned with the historic St Edward's Crown that has been used since the coronation of King Charles II in 1661.

Queen Camilla arrived in the Robe of State originally made for the late Queen Elizabeth in 1953 over an ivory gown embellished with silver and gold floral embroidery and designed by British couturier Bruce Oldfield.

Both left the Abbey in purple Robes of Estate - Charles', previously worn by George VI and Camilla's designed by the Royal School of Needlework and featuring nature-themed embroidery.

"For the first time, insects including bees, butterflies, a beetle and caterpillar feature on the Coronation Robe, drawing on the themes of nature and the environment and reflecting Their Majesties' affection for the natural world," Buckingham Palace said.

The Prince and Princess of Wales, William and Catherine, wore formal robes and mantels over their outfits, with the heir to the throne in the ceremonial dress uniform of the Welsh Guards and his wife wearing a headpiece made of silver and crystal leaves instead of a tiara.

Both she and her daughter Charlotte wore ivory silk crepe frocks adorned with embroidered rose, thistle, daffodil and shamrock motifs - a nod to the United Kingdom's four nations, designed by Alexander McQueen, the same label Kate chose for her wedding dress in 2011.

Charles' siblings also wore traditional robes, while his nieces - Princesses Beatrice, Eugenie, Zara and Lady Louise wore dresses or coats in fuchsia, blue and floral prints respectively.

His son Prince Harry, no longer a working royal, wore morning dress.

Among the celebrity guests were actress Emma Thompson in a red coat adorned with rose designs and U.S. singer Katy Perry, who will perform at the coronation concert in Windsor on Sunday, dressed in a fitted lilac short-sleeved skirt suit with matching opera gloves and statement hat.

Veteran actresses Maggie Smith and Judi Dench, who has portrayed both Queen Elizabeth I and Queen Victoria on screen, chose different shades of blue.

Singers Nick Cave and Lionel Ritchie, who will also perform at Sunday's concert, wore three-piece black suits, while actor Stephen Fry added a touch of colour with a yellow waistcoat.

There were traditional outfits from across the Commonwealth and peers wore red robes.

Block coloured outfits were also popular with U.S and French first ladies Jill Biden and Brigitte Macron dressed in powder blue and pale pink respectively while Ukraine's first lady Olena Zelenska chose a matching sage dress and coat.

Colourful statement hats and fascinators in fuchsia, orange and red peppered the Abbey.