Queen Elizabeth II's death in Scotland indelibly associates the nation with the handover to a new monarch, but her passing also reignites the debate over Scottish independence from the UK.

Thousands of people stood for hours on Sunday to see the 96-year-old's coffin arrive from her Balmoral estate to Edinburgh's Palace of Holyroodhouse, and the formal proclamation of Charles as king.

But there is a strong vein of republicanism in Scotland, and a few heckles could be heard amid the crowds massed along the Royal Mile.

One 22-year-old woman was detained for a breach of the peace for holding a placard with an obscene anti-monarchy slogan just before the proclamation, while there was also some booing.

For some in the crowd, Elizabeth -- and her son King Charles III -- represent the strength of the United Kingdom of Scotland, England, Northern Ireland and Wales.

She was "one of the things that held (the UK) together", noted Archie Nicol, 67, who had earlier paid his respects at the royal Balmoral estate where the queen died Thursday.

Yet many others who expressed their admiration for the late monarch saw it as separate from their desire to be an independent nation.

"The queen clearly had a respect for Scotland," said Nicola Sandilands, 46, a primary teacher.

"The royal family is as much Scottish as they are anything else," she told AFP, while urging them to become "more relevant and current".

However, she acknowledged that the monarch's death "will maybe make it easier to become a republic".

"Some Scots will consider this end of an era a natural moment for a fresh start," Scottish journalist Alex Massie wrote in The Times.

Queen of Scots

The governing Scottish National Party (SNP), which wants another independence referendum following the 2014 "no" vote, is not calling for a republic.

Its founder Alex Salmond coined the term "Queen of Scots" and built close ties with Charles.

And SNP First Minister Nicola Sturgeon was quick to express her "deepest condolences" when the queen died, praising her "extraordinary dedication and service".

But the transition to another monarch based in England -- albeit one educated at a Scottish boarding school, with several Scottish residences and a penchant for kilts -- risks fraying ties.

"The Union is probably in more jeopardy now she is gone," noted veteran journalist Andrew Neil in the Daily Mail newspaper.

"King Charles will love Scotland just as much as the queen. But he simply doesn't have her authority."

A poll by the British Future think tank in June suggested that 45 percent of Scots supported the monarchy while 36 percent wanted a republic.

Meanwhile 51 percent wanted to stay as part of the United Kingdom.

Discretion

Before becoming king, Charles was known for speaking out on a range of issues, including climate change -- a stance praised by Scotland's Daily Record tabloid, which urged him to make the environment his "defining mission" as king.

But as constitutional monarch, he will have to steer clear of anything remotely political, particularly independence.

"The passing of the Crown is a moment of frailty, perhaps even fragility," Adam Tomkins, a constitutional lawyer and professor at the University of Glasgow, noted in The Herald newspaper.

The "burning question", he said, was whether Charles could "emulate his mother in maintaining the discretion by which the monarchy stands or falls".

Queen Elizabeth II never spoke out about independence, although before the 2014 referendum, she told a member of the public she hoped Scots would "think very carefully about the future".

Then-prime minister David Cameron was caught saying that she "purred down the phone" when he reported victory for the anti-independence campaign -- an indiscretion for which he subsequently apologised.

Scottish audience

Charles will have his first audience with Sturgeon on Monday when he returns to Scotland to lead a procession of his mother's coffin to St Giles' Cathedral in Edinburgh, and then hold a vigil.

On Tuesday, her coffin will be flown to London for four days of lying-in-state ahead of the funeral on September 19.

Charles will also visit Northern Ireland and then Wales, completing his tour of all four nations in the UK.

Back in Edinburgh, Theresa Brown, a 51-year-old receptionist, said she was happy for him to stay Scotland's king.

"It's mainly from Westminster I want independence. I don't mind the royal family," she said.