The Duchess of Cambridge is having to self-isolate for 10 days after coming into contact with someone who later tested positive for Covid.
She had been due to spend the day with the Duke of Cambridge to mark the 73rd anniversary of the NHS.
The couple had planned to attend a St Paul’s Cathedral service, and a Buckingham Palace tea for NHS staff.
Kensington Palace said she does not have any symptoms, but is “following all relevant government guidelines”.
It said in a statement: “Last week the Duchess of Cambridge came into contact with someone who has subsequently tested positive for Covid-19.
“Her Royal Highness is not experiencing any symptoms, but is following all relevant government guidelines and is self-isolating at home.”
Catherine’s last public event was a visit to Wimbledon on Friday when she toured the venue and met staff in its museum and Centre Court kitchen.
She also sat with the Duke of Kent in the royal box on Centre Court, and with former British number one tennis player Tim Henman on Court 14 to watch Jamie Murray play in a men’s doubles match.
The duchess is patron of the All England Lawn Tennis Club and a keen tennis fan, but is now likely to miss the men’s and women’s finals at the weekend.
The duchess, who has received both her Covid jabs, began self-isolating on Friday after being alerted that afternoon.
The PA news agency says she follows the royal household testing regime by taking lateral flow tests twice a week.
It reports she additionally took lateral flow tests before visiting Wimbledon and watching England’s Euro 2020 victory against Germany last Tuesday at Wembley with Prince William and Prince George. Both results were negative.
Prince William contracted Covid last spring but was able to carry on with telephone and online engagements while being treated by royal doctors.
The Prince of Wales also caught the virus during the same period but had milder symptoms, although he did lose his sense of smell and taste for a period.