The Queen and the Duke of Edinburgh have "heavy colds" and have decided not to travel today for the start of their Christmas break.They were due to make their traditional train journey this morning from Kings Cross in London to Norfolk to begin their holiday at Sandringham.
However, despite police and staff at the station in numbers, they did not show up and have decided to stay at Buckingham Palace for the time being, where the Royal Standard is still flying.
A palace spokesperson said: "The Queen and The Duke of Edinburgh have heavy colds, and so have decided not to travel to Sandringham today."
The Queen and Duke normally take the same first-class service every year from the capital to King's Lynn, from where they travel on to the royal estate.
Sky Royal Correspondent Rhiannon Mills said there was still time for them to travel before Christmas.
"We'll all be watching out to see whether or not they make that train journey or whether it's decided that because they are feeling under the weather they decide to travel by car instead," she said.
"I don't really think they will want to give a running commentary on their health but you have to remember that the Queen this year turned 90, her husband is 95 years of age, so whenever you hear of anyone that age being unwell it is undoubtedly going to cause some degree of concern."
The Queen and Prince Philip hosted a traditional Christmas lunch for the Royal family on Tuesday.
Also on Tuesday it was announced that the Queen is to step down as patron of a number of organisations.
The list of 25 included Battersea Dogs & Cats Home, Barnardo's, the Rugby Football Union, the British Cycling Federation and the NSPCC.
Other members of the Royal Family will take them on from 2017, Buckingham Palace said.
The Duke of Edinburgh broke formal ties with some of his patronages when he turned 90 in 2011.