Jaswant Singh Chail, 20, has been charged with intending to injure or alarm the Queen under the Treason Act following an incident on Christmas Day at Windsor Castle, the Metropolitan Police said.
Police were called to the castle in Berkshire to reports of an intruder.
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The Queen was celebrating Christmas Day at Windsor Castle at the time.
Chail, from Southampton, was arrested and was allegedly in possession of a crossbow.
His father Jasbir Singh Chail, 57, previously told the Mail Online something had gone ‘horribly wrong’.
He said: 'We are trying to figure out what.
'We've not had a chance to speak to him but are trying to get him the help he needs. We are going through a difficult time. We are trying to resolve this issue and it's not easy.'
The newspaper reported that the Chail family live in the village of North Baddesley, Hampshire.
Metropolitan Police reviewed a video as part of the investigation.
The footage appeared to show a masked figure in a dark hoodie holding a crossbow and addressing the camera with a distorted voice, allegedly referring to a ‘revenge’ mission.
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Police previously said the defendant had been sectioned under the Mental Health Act.
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