A national one-minute silence will be held in honour of the Queen at 8pm on Sunday, Downing Street announced today.
The nation will come together the night before the State Funeral to honour her Majesty after 70 years on the throne. More details were not immediately available.
The Prime Minister's official spokesman said: "The public are invited to come together and observe the National Moment of Reflection to mourn and reflect on the life and the legacy of Queen Elizabeth II.
"The silence can be marked privately at home on your own or with friends and neighbours, out on your doorstep or street with neighbours, or at any locally arranged community events and vigils.
"We encourage local community groups, clubs and other organisations to mark this moment of reflection. And if you are overseas, people are encouraged to mark the silence at their local time.
"The shared national moment of reflection is an opportunity for everyone across the UK to mark the death of Her Majesty and we will set out details of where the Prime Minister will mark it closer to that time."
It will take place while Elizabeth II's coffin lies in state in Parliament, with ministers preparing for mourners to queue for 30 hours to pay their respects.
The government is said to be braced for London to become “full” for the first time, with 1,500 soldiers to help stewards man the queue, and a substantial police operation.
The start of the queue line to 14th Century Westminster Hall - where King Charles was moved by the first rendition to him of God Save the King this morning - had already been set up by 7am today.
No one was yet in the queue at 7am, and government officials are asking people not to join the queue for the lying-in-state yet. They should only do so after full details of the route have been released at 10pm on Tuesday.
The queue will be open 24 hours a day from 5pm Wednesday to 6.30am Monday.
Culture Secretary Michelle Donelan today warned Tory MPs of the huge number of mourners expected to descend on London for the four-and-a-half day vigil.
She told them in a WhatsApp group: “Queues could be up to 30 hours as we are obviously expecting and planning for unprecedented demand."
Downing Street today warned the number of mourners is expected to be "far more" than the 200,000 who saw the Queen Mother lie in state two decades ago.
Mourners are warned they will not be able to take large bags, food and drink or tributes into the Palace, and the queue is "expected to be very long.
“You will need to stand for many hours, possibly overnight, with very little opportunity to sit down as the queue will be continuously moving."
People in the queue will be able to leave to use portable toilets or buy food and come back to the same place, using a system where they're given a wristband to hold their place.
“There is a capability for people to go and use restrooms and return to the queue," No10 said.
There will be food and drink stands en route, though food and drink will not be allowed into Westminster Hall, which will have airport-style security and only small bags allowed.
Commuters may want to "change their working patterns accordingly" as London will be "extremely busy" for the Queen's lying in state, No 10 said.
Asked if Londoners who don't want to see the coffin should work from home, the PM's spokesman said: "London will be busy so some people may wish to adjust their working patterns. Not everyone will be able to do that.”
Asked if there will be any facilities for people who physically cannot queue for 30 hours, he said: "Obviously we want everyone to be able to attend regardless of whether they have disabilities. Our focus is on ensuring they have the information needed to make the decision about what's right for them.
"There will be toilet facilities, there will be first aid available, there will be the ability for people obviously to go and use toilets and return to queues and things like that."
No10 did not deny reports that some world leaders would have to take a bus to Westminster Abbey for the funeral. A spokesman said: “Arrangements for different leaders will vary. We are providing guidance”.
Downing Street did not rule out making the date a permanent bank holiday, saying the issue was always under review but it would not be appropriate to comment now.
Prime Minister Liz Truss will accompany King Charles to Northern Ireland tomorrow, and meet the Queen's coffin when it arrives at RAF Northolt with the Defence Secretary.
