A man cleared of a 2017 sword attack on police outside Buckingham Palace demonstrated to his sister how to stab someone as he plotted a terrorist atrocity last year, a court has heard.

Mohiussunnath Chowdhury, 28, of Luton, is accused of planning attacks against targets including Madame Tussauds and the London Pride parade, two years after a jury acquitted him on charges relating to the 2017 incident.

On Thursday, prosecutor Duncan Atkinson QC told Woolwich crown court that in June last year, unaware their family home had been bugged, Chowdhury was secretly recorded talking to his sister, Sneha Chowdhury, 25.

He said: “Grab them yeah. Actually grabbed it at the side ... Just do one man look just so you get the motion right, come on.”

Atkinson said cut marks were found on a canvas wardrobe in Chowdhury’s room which were “consistent with just such knife training”, and that knife and wooden training swords were later found in a search of the defendant’s bedroom.

In another recording, he told his sister: “I’m doing another attack, bruv … No I’m serious, bro, it’s about time now.”

Sneha Chowdhury, 25, of the same address, is on trial alongside her brother. After the siblings were arrested in July 2019, she told police that the conversations with her brother were light-hearted.

But accusing her of failing to stop her brother, Atkinson said: “Their conversation made all too clear both that he was planning a terrorist attack and that the time of that attack was drawing very close.”

From January 2019, three undercover officers worked to earn Mohiussunnath Chowdhury’s trust and the court heard that he had a conversation with one of them – nicknamed Mikael – about a van attack at a Pride parade.

Mikael asked Chowdhury if he wanted a van for “something like the gay thing” they had discussed, the jury was told. Atkinson said Chowdhury was “animated and smiling” when discussing it and was clearly looking at using the vehicle “as a weapon in a terrorist attack”.

Chowdhury also insisted that Mikael get a gun, the court heard.

Chowdhury was found not guilty of the incident outside Buckingham Palace after telling an Old Bailey jury he wanted to be killed by police and had no intention to hurt anyone but himself.

He denies charges of engaging in conduct in preparation of terrorist acts, collecting information likely to be useful to a person committing or preparing an act of terrorism and disseminating terrorist publications.

His sister denies two charges of failing to disclose information about acts of terrorism.

The case continues.

