The Queen has knighted her main doctor in a private ceremony at Windsor Castle.
Professor Sir Huw Thomas has spent more than 15 years looking after the Royal Family.
He was accompanied by his wife Lady Thomas during the audience.
It is likely to have been a busy few weeks for Prof Sir Huw, after Her Majesty suffered ill health.
She spend a night in hospital on 20 October after being admitted for "preliminary investigations".
She later sprained her back, forcing her to miss the annual Remembrance Sunday ceremony at the Cenotaph.
She has been urged to rest recently, and that advice is likely to have come from Prof Sir Huw.
Her Majesty has been carrying out light duties only, but was seen out driving earlier this month.
The Queen invested Prof Sir Huw with the Insignia of a Knight Commander of the Royal Victorian Order.
The Royal Victorian Order is in Her Majesty's personal gift and is awarded for service to the Royal Family.
Sir Huw is also professor of gastrointestinal genetics at Imperial College London's department of surgery and cancer.
He has been Head of the Medical Household for seven years, and was made a Knight Commander at the start of 2021 in the New Year Honours list.
Speaking to Imperial College at the time, he said it had been a "busy couple of years" for his royal work, adding that he was "very grateful to have been recognised for my service to date".
He continued: "You very much become part of that organisation and become the personal doctor to the principal people in it, who are patients just like other patients.
"With the pandemic, the key priority of the Medical Household is trying to make sure that the people under its care are kept safe."
Details of the investiture appeared in the Court Circular - the daily record of official royal engagements.