King Charles has returned to London from Balmoral, pausing to share his grief with mourners gathered outside Buckingham Palace and immediately taking up the royal duties of a monarch.

The new King will hold his first audience with new Prime Minister Liz Truss and will deliver a national television address on Friday evening (UK time).

Arriving at Buckingham Palace after their journey from the royal Scottish estate, Charles and wife Camilla, now officially known as Queen Consort, stepped out of the royal car to huge cheers from a crowd gathered outside the palace.

The King then proceeded to shake hands with dozens of well-wishers and look at floral tributes to his mother for at least ten minutes.

Several members of the public sang God save the King and one said “Love you Charles!”.

Earlier the grief-stricken Charles was glimpsed for the first time since his accession to the throne as he departed Birkhall, his private home on the Balmoral estate, by car at around 11.15am on Friday.

With Camilla in the front passenger seat and Charles in the back, the new King wore a sombre expression in his mourning clothes of a black suit and tie.

Charles and Camilla rushed to be at the Queen’s bedside when she fell gravely ill. The couple stayed overnight at Balmoral, where the Queen died peacefully aged 96 on Thursday afternoon.

Period of mourning

In one of the first decisions of reign, the King gave the order that a period of “Royal Mourning” for the Queen will be observed from now until seven days after her funeral, likely be held on September 19.

Royal Mourning will be observed by members of the royal family, royal household staff and representatives of the royal Household on official duties, together with troops committed to ceremonial duties.

Royal salutes will be fired in London on Friday at 1pm in Hyde Park by the King’s Troop Royal Horse Artillery, and at the Tower of London by the Honourable Artillery Company, with one round being fired for each year of the Queen’s life.

Flags at royal residences were at half-mast on Thursday and will remain half-masted until 8am on the morning after the final day of royal mourning.

Formal accession set

On Saturday morning, an Accession Council – the formal proclamation of Charles as King – will take place at St James’s Palace in London.

The first public proclamation of the new sovereign will then be read in the open air from the Friary Court balcony at St James’s Palace by the Garter King of Arms.

Charles will hold audiences, and the media will be briefed by the Earl Marshal, who is in charge of the accession and the Queen’s funeral, on the coming days.

-with AAP