The Queen has not attended church on Christmas Day because she is still suffering from a heavy cold.
Buckingham Palace said she was staying indoors to help her recover but added that she would still participate in the family’s Christmas Day celebrations.
Prince Philip, Prince Charles, Prince Harry and others attended church at the Queen’s Norfolk estate, Sandringham.
The Duke and Duchess of Cambridge went to church in Berkshire, where they are spending Christmas with the Middletons.
Nicholas Witchell, BBC royal correspondent, said the Queen’s absence from the church service – the first time she has missed the service “in many years” – is understood to be a “precautionary measure”.
Our correspondent said there was “no sense of undue concern” from Buckingham Palace.
BBC reporter Emilia Papadopoulos said about 3,000 people had waited for the royals at Sandringham – some from 06:00 GMT.
She said although there was “a lot of disappointment” among the crowds, Prince Charles and Prince Harry had both spoken to people after the service and most had left saying it had been “well worth the wait”.
The Queen and Prince Philip began their Christmas break this week one day late, postponing their trip because they were both suffering from colds.
They flew from Buckingham Palace to the Norfolk estate by helicopter on Thursday, having missed a train on Wednesday.
A palace spokesman said: “Her Majesty the Queen will not attend church at Sandringham this morning.
“The Queen continues to recover from a heavy cold and will stay indoors to assist with her recovery.
“Her Majesty will participate in the Royal Family Christmas celebrations during the day.”
Prince William and the Duchess of Cambridge are spending Christmas with the Middleton family in Bucklebury, Berkshire.
The Queen’s granddaughter Zara Tindall and her husband Mike did not attend the service.
They announced on Christmas Eve that they had lost their second baby.
In her annual televised Christmas Day address, which was recorded in advance, the Queen said she drew strength from “ordinary people doing extraordinary things”.
Volunteers, carers, community workers and good neighbours are unsung heroes whose quiet dedication makes them special, she will say.
She will also praise the achievements of the UK’s Olympians and Paralympians.
“Having discovered abilities they scarcely knew they had, these athletes are now inspiring others,” she will say.
Her Majesty will also reflect on the achievements of the Duke of Edinburgh’s Award, which celebrated its 60th anniversary this year, and The Prince’s Trust, which was 40 years old in 2016.
The address was recorded before Her Majesty travelled to Sandringham.