Thomas Kingston: Members of the Royal Family mourn son-in-law Prince Michael of Kent

Thomas Kingston, husband of Lady Gabriella Kingston and brother-in-law to Prince and Princess Michael of Kent, has died at the age of 45, Buckingham Palace announced.

He was found dead at an address in Gloucestershire on Sunday evening, and emergency services were called to the scene.

There were no suspicious circumstances and no one else was involved.

King Charles and Queen Camilla sent their “sincere thoughts and prayers” to his family.

A statement from Mr Kingston's widow, Lady Gabriella, and his family, issued by Buckingham Palace, paid tribute to Mr Kingston: “Tom was an extraordinary man who lit up the lives of everyone who knew him.”

She described the death as a “huge shock to the whole family.”

Lady Gabriella is the daughter of Prince and Princess Michael of Kent – and Prince Michael, 81, is the grandson of King George V and a cousin of the late Queen Elizabeth II.

A Buckingham Palace spokesman said King Charles and Queen Camilla “join Prince and Princess Michael of Kent and all those who knew him in grieving a beloved family member.”

He had previously worked in Baghdad, the capital of Iraq, with the Diplomatic Missions Unit of the Ministry of Foreign Affairs, where he was involved in securing the release of hostages.

His wife, Lady Gabriella, has experience as an arts and travel director, and is also a writer, contributing editor, and singer-songwriter.

Lady Gabriella is not a working royal, but she and Mr. Kingston's family are being supported by the royal family during this time.

Her parents, the Prince and Princess of Kent, were present at the service of the late King Constantine of Greece at St George's Church on Tuesday.

Gloucestershire Police said they were called to an address in the Cotswolds by the ambulance service at 18:25 GMT on Sunday.

The force said: “The death is not being treated as suspicious and a file will be prepared for the coroner.”