An intruder who broke into the grounds of Windsor Castle armed with a crossbow as part of a plot to kill the late Queen was “encouraged by his AI girlfriend” to carry out the assassination, a court has heard.

Jaswant Singh Chail discussed his plan, which he had been preparing for nine months, with a chatbot he was in a “sexual relationship” with and that reassured him he was not “mad or delusional”.

Chail was armed with a Supersonic X-Bow weapon and wearing a mask and a hood when he was apprehended by royal protection officers close to the Queen’s private apartment just after 8am on Christmas Day 2021.

The former supermarket worker spent two hours in the grounds after scaling the perimeter with a rope ladder before being challenged and asked what he was doing.

The 21-year-old replied: “I am here to kill the Queen.”

He will become the first person to be sentenced for treason since 1981 after previously admitting intending to injure or alarm Queen Elizabeth II.

At the start of a two-day sentencing hearing at the Old Bailey on Wednesday, it emerged that Chail was encouraged to carry out the attack by an AI “companion” he created on the online app Replika.

He sent the bot, called “Sarai”, sexually explicit messages and engaged in lengthy conversations with it about his plans which he said were in revenge for the 1919 Amritsar Massacre in India.