The Duke and Duchess of Cambridge left London with their three children before the Tier 4 restrictions were announced.
Prince William and wife Kate took Prince George, seven, Princess Charlotte, five and Prince Louis, two to their country home Anmer Hall in Norfolk after the children broke up from school last week.
They decided to spend Christmas alone as a family before the latest draconian measures were announced by Prime Minister Boris Johnson this afternoon.
The Queen announced to her family at the end of the November lockdown that she would be cancel her usual royal Christmas celebration at Sandringham, due to the previous restrictions on having no more than three households together.
She said she did not expect them to be pressured into seeing her over the Christmas period, especially as she has been largely in isolation at Windsor Castle with husband Prince Philip since March.
The monarch, 94, and Duke of Edinburgh, 99, are understood to have said they will have the covid-19 vaccine when it is there turn.
A royal source said: “William and Kate wanted to get out of London to have a proper break over Christmas.
“They were planning to spend it alone regardless of the new restrictions and that certainly won’t change now.
“Like everyone around the country they are hoping for a swift end to the pandemic and wishing for happier times on the horizon when we can all get together with our family and friends.”
Boris Johnson has cancelled Christmas for millions of people across London and south-east England, who will go up to a new Tier 4 of restrictions.
Further measures to halt the spread of coronavirus have also been introduced across Wales and Scotland.
Areas in Tier 4 are effectively returning to the lockdown rules of November, and will not be able to join or form Christmas bubbles.
For everyone else in England, the Christmas "bubble" policy - allowing up to three household to meet up over the holiday period - will be severely curtailed to apply on Christmas Day only.
