A man who was arrested at Windsor Castle on Christmas Day while in possession of a crossbow has been detained under the Mental Health Act.
The 19-year-old was found by police on Saturday morning within the grounds of the castle in Berkshire where the Queen is in residence.
He was arrested on suspicion of breach or trespass of a protected site and possession of an offensive weapon.
The Metropolitan Police said on Sunday that the man was taken into custody and has undergone a mental health assessment.
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."