Following a Sunday night horse-related incident involving his sister, Princess Anne, King Charles is being kept "closely informed".

At her Gatcombe Park residence, the 73-year-old Princess Royal had mild head injuries and a concussion. Renowned for her riding skills, Anne reportedly suffered brief memory loss following the event The Telegraph reports.

Before moving her to Southmead Hospital in Bristol for more tests and observation, emergency services were sent to the estate to provide first medical treatment.

Buckingham Palace said: "The Princess Royal sustained minor injuries and a concussion following an incident on the Gatcombe Park estate yesterday evening. Her Royal Highness is still in Southmead Hospital, Bristol, for surveillance purposes and should fully and quickly recover. The King joins the complete royal family in expressing his best love and well-wishes to the princess for a quick recovery; he has been kept especially informed.

This event has caused Princess Anne to postpone her weekly engagements. "On doctor's advice, Her Royal Highness's engagements for the week ahead will be postponed," the Palace said. Her Royal Highness apologises to anyone who might be annoyed or let down as a result. Though Her Royal Highness will be unable to attend the State banquet tomorrow, the Japanese State Visit will go as scheduled.

Princess Anne stayed overnight at the hospital, and her medical experts verified her injuries matched those of a horse kick. She got first care at her Gloucestershire estate, where an air ambulance and other emergency services were sent. She was then hospitalised. The incident claimed no injuries to anyone else.