Members of the public began filing past at 5pm local time and will have until 6.30am on the day of the funeral, by which time several thousands are expected to have queued for hours to pay their respects to the Queen.
The UK capital on Wednesday unleashed a major operation to manage the several thousands of people expected to queue over the next few days to pay their respects to Queen Elizabeth II as she lies in state at Westminster Hall.
A ceremonial procession is scheduled for Wednesday afternoon that will see the coffin travel in a gun carriage from Buckingham Palace to the Palace of Westminster, or the Houses of Parliament building.
'We, too, smile knowing that you and grandpa are reunited now, and both together in peace'
Quoting Shakespeare, he noted: "As Shakespeare said of the earlier Queen Elizabeth, she was a pattern to all princes living."
Thousands lined the route to catch a glimpse as Queen Elizabeth II's coffin, seen in public for the first time, made its journey on Sunday from Balmoral Castle in Aberdeenshire to arrive at the late monarch's official Scottish residence of Holyroodhouse Palace in the capital city of Edinburgh.
Prior to the state funeral, the late British monarch will lie-in-state at Westminster Hall nearby for four days to allow the public to pay their respects.
In their first phone call since Truss assumed office earlier this week, Modi conveyed his condolences on the death of Queen Elizabeth II on behalf of all Indians and paid tribute to the 96-year-old late monarch's "lifetime of service".
"God save the King" were the words with which those gathered reaffirmed the proclamation made by the clerk of the council.
Charles will be formally proclaimed as King at the Accession Council at 10am local time on Saturday in the State Apartments of St. James's Palace, Buckingham Palace has said. It will mark the first time in history that the ceremony will be televised.
Churches also tolled their bells, after the Church of England sent out guidance to parishes, chapels and cathedrals across the country encouraging them to open for prayer or special services. Major sporting events, including football and cricket matches, have been postponed as a mark of respect.
King Charles III, Britain's new monarch who ascended to the throne on the death of his mother Queen Elizabeth II, has a strong connection with India and its age-old traditions of Yoga and Ayurveda.
Queen Elizabeth II, who died aged 96 on Thursday, was the first British monarch to accede to the throne after India's Independence from colonial rule in 1952 and admired the 'richness and diversity' of India where she made three State Visits over the course of her reign -- in 1961, 1983 and 1997.
"The Queen died peacefully at Balmoral this afternoon," Buckingham Palace announced in a statement on Thursday.
The death of the Queen is known in official circles in the United Kingdom as Operation London Bridge, the protocol for which has been triggered when Buckingham Palace announced the death of the 96-year-old monarch on Thursday evening.
Queen Elizabeth II made 3 State visits to India -- in 1961, 1983 and 1997.
The 96-year-old monarch has been suffering from age-related mobility issues and has cut down her travels, including appointing new Prime Minister Liz Truss in Scotland earlier this week.
Prime Minister Liz Truss has unveiled one of the United Kingdom's most diverse cabinets, with key frontline posts going to ethnic minority members of Parliament, including Indian-origin Suella Braverman as the home secretary.
The 42-year-old barrister, who until now served as the Attorney General in the Boris Johnson led government, was among the first contenders to throw her hat in the ring to replace Johnson as Tory leader and Prime Minister.
Conservative Party leader Liz Truss was on Tuesday formally appointed as Britain's new Prime Minister by Queen Elizabeth II, becoming the third female premier of the country.