Princess Anne's husband, Admiral Timothy Laurence, has contracted COVID-19, Buckingham Palace sources have confirmed. They also said this development meant Sir Timothy and Anne won't join Her Majesty at Windsor over the weekend of Christmas celebrations.
Whilst it confirmed the Princess Royal and her husband won't travel to Windsor to celebrate Christmas, the palace has remained tight-lipped on who may join the Queen instead.
Sir Timothy is currently recovering from the virus and is understood to be self-isolating at Gatcombe Park, where he lives with his wife Princess Anne.
Sources said the Princess Royal is also isolating at her home in Gloucestershire.
According to the current Government regulations on Covid, Princess Anne - who never shared her vaccination status - does not need to self-isolate for 10 days if she is fully vaccinated.
The Government, in a bid to fight the rise of the Omicron variant in the country, strongly recommends anyone aged five years and over who has had contact with a person who tested positive for Covid and is not legally required to enter quarantine "to take a rapid lateral flow device test every day for seven days or until 10 days since their last contact with the person who tested positive for COVID-19 if this is earlier".
The report on Sir Timothy comes just hours after the Queen made the decision to scrap her traditional festive break on the Sandringham Estate amid the rise of Covid infections.
The move, a royal source said, was a "personal one taken after careful consideration" which "reflects a precautionary approach".
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However, the source said, the monarch will receive visitors over the Christmas period while remaining mindful of Covid regulations and safety measures.
This marks a positive change when compared to last year, when the Queen celebrated Christmas only in the company of her beloved husband Prince Philip and their loyal staffers.
Princess Anne's absence from the Christmas celebrations and the Queen's decision to scrap her trip to Sandringham are just two of the adjustments made by Her Majesty on her first winter holidays as a widow.
Last week, a royal source announced the monarch had decided against hosting her traditional pre-Christmas party, open to the extended members of her family.
This lunch normally takes place at Buckingham Palace but, after last year's cancellation due to Covid, the monarch was planning to host it at her Berkshire residence.
On Christmas Day, the Queen normally attends the 11am service in the company of her relatives and guests staying at the palace.
It isn't yet clear whether the monarch and her loved ones will step out of Windsor Castle this year for the service or will refrain from doing so in order to avoid a gathering of royal well-wishers.
This shielded Christmas comes also in the wake of a period troubled by health issues for the Queen.
Health concerns for the monarch were first made public on October 20, when the palace announced she had agreed to cancel a planned trip to Northern Ireland and rest for a few days following her doctors' advice.
She has since scrapped all her engagements outside of palace walls - including the attendance at the National Service of Remembrance.
However, the Queen has continued to carry out her day-to-day duties as sovereign, including dealing with the Government's red boxes.
Moreover, she has regularly held audiences with foreign ambassadors, diplomats and honourees either via video link or in person.
While she hasn't worked outside of Windsor Castle for two months, she is known to have stepped out of her home on at least two occasions.
In early November, she had travelled via helicopter to Sandringham for a long weekend on her estate.
And a few weeks later, she attended the double christening of Lucas Tindall and Sienna Elizabeth Mapelli Mozzi.