A man who was arrested within the grounds of Windsor Castle on Christmas Day while in possession of a crossbow has been detained under the Mental Health Act.

Officers from Thames Valley Police (TVP) and the Metropolitan Police responded to a security breach on Saturday at around 8.30am within the grounds of the castle in Berkshire where the Queen is in residence.

A 19-year-old man, from Southampton, was arrested on suspicion of breach or trespass of a protected site and possession of an offensive weapon.

The Metropolitan Police said the man was taken into custody and has undergone a mental health assessment.

READ MORE: MAN ARRESTED AFTER BREACHING WINDSOR CASTLE ON CHRISTMAS DAY

He has since been sectioned under the Mental Health Act and remains in the care of medical professionals, the force added.

A spokesperson from Scotland Yard said: “Security processes were triggered within moments of the man entering the grounds and he did not enter any buildings.

“Following a search of the man, a crossbow was recovered.”

They added: “Inquiries into the full circumstances of this incident are being progressed by Metropolitan Police specialist operations.”

A Buckingham Palace spokeswoman declined to comment.

The Queen spent Christmas Day at Windsor Castle and was expected to have lunch with the Prince of Wales and the Duchess of Cornwall, and the Earl and Countess of Wessex.

Charles, Camilla, Edward and Sophie, along with their children Lady Louise and James, Viscount Severn, attended a church service in St George’s Chapel, in the castle grounds, at 10.45am on Christmas morning.

In May, TVP arrested a 29-year-old woman and a 31-year-old man, both from London, after a report that two trespassers had been in the grounds of the Royal Lodge at Windsor Great Park on the afternoon of April 25.

Police said there was no risk to any individual on the site.

Officers were also called to the Duke of York’s home after a woman reportedly talked her way into his mansion on April 19.

A 43-year-old woman spent 20 minutes in the grounds of Royal Lodge after telling security guards she was having lunch with the Queen’s son, according to the Sun newspaper.

She later made her way into the home and was held after asking a member of staff where she could find the duke, and saying she was his fiancee and had come to marry him, the newspaper reported.

The article claimed the woman had arrived in Windsor in a taxi and had even persuaded the duke’s security guards to pay her fare.

It is not known if Andrew was at the home he shares with his former wife Sarah, Duchess of York.

TVP said the woman was stopped and later sectioned under Section 136 of the Mental Health Act but there was no risk to anyone on the site.