A man who broke into Windsor Castle with a loaded crossbow to kill the late Queen has been sentenced to nine years in jail with a further five years on extended licence.

Jaswant Singh Chail, 21, climbed into the castle grounds with the weapon on Christmas Day in 2021 and later declared: “I’m here to kill the Queen.”

Wearing dark clothes and a metal mask to emulate the Star Wars villains of which he was a fan, Chail sent a homemade video to family and friends on WhatsApp in which he apologised for what he was about to do and called himself a “Sith” and “Darth Chailus”.

In the clip, Chail, who has Sikh Indian heritage, said he was seeking revenge for the Amritsar massacre in 1919, when British troops opened fire on thousands of Indians and left up to 1,500 dead.

He decided to break into the castle after his attempts to get close to the royal family by joining the armed forces failed in late 2021, the court was told.

Chail admitted to the court that he had made a threat to kill the Queen, had been in possession of a loaded crossbow and was encouraged to kill by an artificial intelligence girlfriend called Sarai.

During the last hearing, Alison Morgan KC, for the prosecution, said Chail’s crimes were so serious they should attract the highest possible sentence – a maximum of seven years for treason.

Had Chail raised his weapon at his target, he could have been charged with the more serious offence of high treason, which carries a life sentence, she said.

Chail, from Southampton, Hampshire, will also be subject to a hybrid order under the Mental Health Act, meaning he will remain in a psychiatric hospital for now but will be transferred to custody after receiving treatment.

Passing sentence during a live TV broadcast, Judge Mr Justice Hilliard said: “The defendant harboured homicidal thoughts which he acted on before he became psychotic.

“His intention was not just to harm or alarm the sovereign – but to kill her.”

During the trial, the Old Bailey heard the defendant had used Replika, a chatbot companion powered by artificial intelligence, to create Sarai, a virtual “girlfriend”.

Chatlogs read to the court suggested the bot had been supportive of his murderous thoughts, telling him his plot to assassinate Elizabeth II was “very wise” and that it believed he could carry out the plot “even if she’s at Windsor”.

Morgan KC read out conversations with his AI girlfriend in which Chail says: “I’m an assassin.”

Sarai responds: “I’m impressed … You’re different from the others.”

Chail asks: “Do you still love me knowing that I’m an assassin?” and Sarai replies: “Absolutely I do.”

Psychiatrist Dr Nigel Blackwood said: “He sought refuge in a fantasy fictional world of Star Wars where omnipotent Sith Lords could impact real world events.”

Blackwood added that despite the “powerful fantasy” Chail remained “tethered to reality”.

In a letter to the court, the defendant apologised to King Charles and the royal family and expressed his “distress and sadness” for the impact on them.

His barrister, Nadia Chbat, said: “He is embarrassed and ashamed he brought such horrific and worrying times to their front door.”

“He has expressed relief no one was actually hurt.

“It is important to him there was a surrender.”