Prince William and Kate may be forced to spend Christmas away from the Queen with their three young children potentially considered a risk to their elderly grandparents.
Like the rest of Britain, the monarch, 94, and Duke of Edinburgh, 99, can form a Christmas bubble consisting of no more than two other households between December 23 and 27.
This means the annual Sandringham mass family get together is off, though HM is consulting with the rest of the royals as she draws up her bubble.
The Queen and Prince Philip are in the highest risk bracket, with the latter's pre-existing health issues, that saw him hospitalised last Christmas, a key factor in the decision.
"They will sort it out between them; it will be about what’s practical," a source told the Daily Telegraph, adding that the potential risks surrounding young children who have been mixing with others at school would "clearly" be taken into account.
Prince George is seven, Princess Charlotte is five and Prince Louis is two, meaning they are unlikely to be display severe symptoms of Covid if they were to get it.
William and Kate, with their three children, could opt to spend Christmas with the Middleton family in Berkshire, having celebrated the festive period with the Queen for three years in a row.
However, Carole and Michael Middleton have two other children as well as Kate - Pippa Matthews and James Middleton, meaning one of the three offspring would not be allowed to gather for the festive celebrations.
Her Majesty could instead pick the Prince of Wales and the Duchess of Cornwall as one third of her bubble, but this would mean Camilla would be unable to see her children and grandchildren.
The Queen may invite her youngest son Edward, with his wife Sophie and their children Lady Louise Windsor, 16, and 12-year-old Viscount Severn, who form one household.
Prince Edward and his family are considered a more likely option to join the Queen's bubble, with his older children to find social distancing easier than some of their younger relatives.
Sophie, Countess of Wessex, is also said to be particularly close to the Queen.
Or the Queen could choose her daughter, the Princess Royal, or the Duke of York, but they both have grown-up children, with whom they might form a bubble with.
The Queen will also have to decide whether she will remain at Windsor Castle, where she and Philip spent the second lockdown, or move to Sandringham.
If they choose the latter, it is unlikely the annual walk to St Mary Magdalene Church for the Christmas Day service will take place, in order to avoid crowds.
The Telegraph reports a Boxing Day shoot at Sandringham could be on the cards, with up to 30 people allowed at outdoor sporting events.
The Queen has spent Christmas Day at Sandringham for the last 37 years.
There were reports in September that an uprising among royal staff had left the Queen "furious" and contemplating spending Christmas away from her traditional festive home.
Sandringham staff were said to be unhappy about the idea of being stuck in Her Majesty's bubble for four weeks during the holiday period.
This would mean not seeing their own families for an extended period opening up the possibility of Christmas at Windsor.
Reports claimed the staff - understood to include around 20 cleaners and laundry and maintenance workers - had put their foot down and told HRH "enough is enough".