A dog barking and sporadic gun salutes were among the only sounds as hushed crowds watched King Charles III on Monday lead his siblings in poignant procession behind their mother's coffin through the historic heart of Edinburgh.

Well-wishers packed along the Scottish capital's iconic Royal Mile, holding up their mobile phones in near-silence to film the hearse carrying Queen Elizabeth II as it crept out of Holyroodhouse Palace.

Kilted soldiers from the Royal Regiment of Scotland marched slowly alongside the casket -- covered with a royal standard and wreath of white flowers -- on the roughly kilometre-long (0.6-mile) journey to the 14th-century St Giles' Cathedral.

The new king -- clutching a baton -- walked behind in the full ceremonial military uniform of a Field Marshal with the green Thistle Sash across his chest and the Order of Merit around his neck.

His sister Princess Anne and brother Prince Edward were also decked out in uniform beside him, while Prince Andrew -- stripped of his "His Royal Highness" title over a sex assault scandal -- wore a black mourning suit.

The sombre atmosphere was briefly broken by a heckler who shouted at Andrew before being dragged away.

The procession through Edinburgh was the latest step in the odyssey of carefully choreographed mourning since the queen passed away at her beloved Scottish retreat Balmoral on Thursday.

The death of the monarch in Scotland has been highly symbolic -- as widespread respect for the queen mingles with a drive for independence.

Upon arrival at the cathedral -- which had police snipers stationed on its roof -- the coffin was carried by military pallbearers up the steps and placed on a catafalque before the altar for a thanksgiving ceremony.

The Crown of Scotland was placed on the casket that will lie in rest under the cathedral's vaulted stone ceiling for members of the public to view for almost 24 hours.

- 'Once in a lifetime' -

People had begun arriving from the early hours of the morning for the chance to file past the coffin of the only monarch most of them have ever known.

Authorities warned mourners to prepare for long waits and bring their own food if they wanted to see the casket, which will depart for London on a military plane on Tuesday.

Graham Lumsdon, 56, a former miner who served in the military for 22 years, had travelled 145 kilometres from Newcastle in northeast England to be able to have a last chance to be near the queen.

"I'm going to get suited and booted, put my medals on and pay my respects to Her Majesty," he told AFP.

He recalled how he had met the queen over 40 years before as a schoolboy when she had come to visit his hometown with her husband Prince Philip -- and now he wanted to bid her farewell.

"It's a once in a lifetime moment, it's never going to happen again for me in my lifetime. I  will never see another queen buried," he said.

Sam Whitton, an 18-year-old studying sports science in Glasgow, vowed to stay "as late as I need" to get into the cathedral as he waited with his brother and a friend.

"I just thought it was a piece of history," he said.

"You obviously knew she was going to die but it was never planned for, you always thought she would be here."