Liz Truss and Sir Keir Starmer are among those in attendance to commemorate the late monarch after her remarkable reign.
Ms Truss arrived at Westminster Abbey with her husband Hugh O’Leary shortly before 10.30am and was greeted by members of the clergy and shook their hands in turn before taking her seat in the abbey.
While Labour leader Sir Keir arrived at Westminster Abbey shortly before 9.40am.
Politicians from across the land have gathered to pay their final respects to Queen Elizabeth II after days of mourning and an outpouring of grief in all four nations of the United Kingdom.
It is not just British politicians, either.
Sir Keir Starmer and Liz Truss
PA/POOL
Prime Minister Liz Truss and husband Hugh O'Leary arrive at the state funeral of Queen Elizabeth II
James Manning
Heads of state and overseas government representatives, including foreign royal families, governors-general and realm prime ministers initially gathered at the Royal Hospital, Chelsea, on Monday morning.
They then travelled under collective arrangements to Westminster Abbey, now over 1,000 years old, ahead of arguably the biggest funeral in Britain's history.
And the outpouring of grief extended beyond the walls of the abbey.
Thousands have lined the streets or taken up spots in one of the city's public parks, notably Green Park and Hyde Park, to get a view of Her Majesty's coffin before it is driven to Windsor.
It is believed Queen Elizabeth II's funeral will be the "largest single policing event ever undertaken" in London.
Liz Truss and Sir Keir Starmer paying their respects to Queen Elizabeth II earlier this week
POOL
The event on Monday is expected to be bigger even than the policing response around the 2012 Olympics and this year's Platinum Jubilee celebrations.
In a security briefing to the media, Deputy Assistant Commissioner Stuart Cundy said “almost every force in the country” had officers involved in the policing operation around the Capital.
The senior commander said some 20,000 officer shifts were being worked throughout the week leading up the funeral.
He said the policing operation would increase significantly as the funeral approaches, but could not give details of the number of officers likely to be involved.
DAC Cundy said the event was a “truly national policing operation, and difficult to compare to any other event".