The nation is in mourning as the news of the death of Queen Elizabeth II came in on Thursday afternoon.

Her death brings an end to an era and a 70-year reign, the longest in history.

What happens next is ‘Operation London Bridge’ a not so secret plan, which has been leaked several times over the years, swings into action. The plan is designed to ensure not only that the news of the queen’s death was broken in a dignified manner and her memory commemorated, but also to ensure the continuation of the royal throne as Britain’s head of state.

Named after a former London landmark that was forever ‘falling down’ Operation London Bridge was the code word attributed to a formally planned sequence of events that would occur after the death of the British monarch.

Since the news of Her Majesty’s death parliament has been recalled, Union flags have been lowered and flown at half-mast on royal residences, government buildings and military establishments and books of condolence opened at British embassies across the world.

Queen Elizabeth II will lie in state in Edinburgh and Westminster as part of 10 days of national mourning beginning on Friday.

According to the expected plan, after the British Monarch dies her replacement takes over immediately. This means that after Queen Elizabeth II died on Thursday her son Prince Charles automatically became monarch – and in this case, he became King Charles III

King Charles III and wife Camilla, the Queen Consort, will return to London, having spent Thursday night with immediate family at Balmoral, where the Queen died.

On Friday he is expected to meet Liz Truss and help formalise funeral arrangements.

MPs will get the chance to make their own tribute to the Queen in the Commons from 12 noon on Friday, before a further unusual session from 2pm on Saturday.

At the Saturday session the council will formally declare the death of the monarch and the accession of the successor to the throne, according to the Privy Council, a formal advisory body to the monarch. The accession Council is presided over by the lord president of the Privy Council – Conservative MP and leader of the House of Commons, Penny Mordaunt.

After the news King is declared by the Accession Council a proclamation will be read at St James’s Palace, accompanied by gun salutes and the national anthem will be played with the words “God save the King”

Having received a motion of condolence in Westminster Hall, King Charles III will then begin a tour of the UK home nations including Northern Ireland and Wales, with a brief ceremony in each.

As the Queen died in Scotland, her body will lie in St Giles’ cathedral in Edinburgh for 24 hours to allow close family to pay their respects.

As the period of mourning continues, the Queen will be moved to London on Saturday, where her coffin is expected to lie in state for three days at Westminster Hall in advance of her state funeral at Westminster Abbey in central London, a ceremony presided over by the Archbishop of Canterbury.

The queen’s funeral is expected to be held on the tenth day of mourning, which is Sunday 18 Sept at London’s Westminster Abbey. Heads of state and other VIPS from abroad will be in attendance. She will finally be laid to rest at St George’s Chapel at Windsor Castle, where her late husband, Prince Philip, and both of her parents, the Queen Mother and George VI, are also buried.

The day of her funeral and that of the coronation of King Charles III will both be national holidays.