Camilla, Duchess of Cornwall, has tested positive for Covid, it was announced on St Valentine’s Day.

First, it was Charles who cancelled an event after testing positive for the virus on Thursday last week.

Camilla carried out a string of engagements the same day after testing negative herself.

A Clarence House spokesman said on Monday: “We continue to follow government guidelines.”

It is the first time the duchess has caught coronavirus, while Charles has the virus for a second time. He tested positive for Covid in March last year but his symptoms were relatively mild.

Charles, 73, met the Queen at Windsor Castle two days before testing positive for the virus but a royal source said on Thursday that the monarch had shown no symptoms. The Queen, who is 95, is set to begin events to mark the Platinum Jubilee of her reign.

The Queen has said it is her “sincere wish that, when that time comes, Camilla will be known as Queen Consort as she continues her own loyal service”.

This overturns a previous undertaking, given when Charles and Camilla got married in 2005 — it was the second marriage for both — that she would be known as the “Princess Consort”.

It has subsequently been reported that Charles and Camilla will be crowned together, when she will get to wear the Kohinoor diamond, which is kept in the Tower of London as part of the Crown jewels.

It was worn when the Queen Mother became the “Queen Consort” when her husband was crowned George VI on May 12, 1937, following the abdication of his brother, Edward VII, in December 10, 1936. The latter wanted to marry the divorcee, Wallis Simpson.

Today, only one of the Queen’s four children — Edward — hasn’t been through a divorce.

On Wednesday evening last week, Charles and Camilla made their first appearance together since the Queen’s announcement at a British Asian Trust dinner heaving with Indian celebrities.

A group photo showed Charles and Camilla with the chancellor Rishi Sunak and his wife, Akshata, who wore an embroidered full-length white dress; the home secretary Priti Patel in a purple and gold lehnga; and the Serum Institute of India CEO Adar Poonawalla, who spends more time in London than in Pune, and his wife Natasha in a dazzling sari.

Charles, always in his element when he is with Indians, found time to talk to many other prominent Indians, among them the Punjabi film director Gurinder Chadha. Indians, being Indians, naturally wanted to get up close to the future king and snatch a photo with him and Camilla.

Charles received rousing cheers when he began his speech by saying: “I cannot quite believe it is almost two years to the day that both my Mehbooba and myself were able to be with all of you to celebrate the work of the British Asian Trust.”

Those socially ambitious Indians left off the guest list were metaphorically slitting their wrists. Maybe they were the lucky ones as everyone who was there has been frantically testing for Covid.

The joke in London is that the curse of the Koh-i-Noor has struck again. The diamond, steeped in blood, is said to bring bad luck.

And Camilla hasn’t even worn it yet.