Queen Elizabeth II returned to royal duties at her Windsor Castle residence on Tuesday, carrying out her first engagements since fears emerged that she could have contracted coronavirus last week.

The scare arose after Prince Charles, her eldest son and heir to the throne, tested positive for Covid-19 for the second time, two days after meeting the 95-year-old monarch in Windsor, west of London.

His wife Camilla, the Duchess of Cornwall, also then tested positive, and the couple has been self-isolating since according to aides.

Buckingham Palace has not revealed whether the queen has taken any Covid test herself.

On Tuesday the monarch — who this month marked 70 years on the throne — held two virtual audiences from Windsor, meeting via video link with newly appointed ambassadors from Estonia and Spain.

The queen, who was isolated in her own “bubble” at Windsor when the pandemic struck in early 2020, has had health problems in the past year that forced her to take a step back on medical advice.

The palace was criticised for a lack of transparency over the issue, eventually confirming that she had spent a night in the hospital in October for “preliminary” tests, the nature of which have never been specified.

However, following the death of her husband Prince Philip in April last year, she has been once again filling up her diary for a year of celebrations to mark her record-breaking reign.

On February 5, the eve of the 70th anniversary of her accession to the throne, she held a reception for locals at Sandringham, her estate in eastern England.

It was reportedly her largest in-person public engagement since the autumn health scare.

Four days of national festivities to mark her Platinum Jubilee are planned for early June.