A man who was cleared over a sword attack on police outside Buckingham Palace went on to plan a series of terror attacks, a court has heard.
Mohiussunnath Chowdhury, 28, was found not guilty of a terror charge over an incident outside the palace in 2017, Woolwich Crown Court heard.
He is accused of later planning attacks on places including London's Madame Tussauds and London Pride parade.
Mr Chowdhury, of Kirkwood Road, Luton, denies the charge.
He appeared in court alongside his sister, Sneha Chowdhury, 25, who is accused of doing nothing to stop his plans.
Ms Chowdhury, of the same address, denies two charges of failing to disclose information about acts of terrorism.
Woolwich Crown Court heard that, in the attack outside Buckingham Palace in August 2017, two unarmed officers suffered cuts to their hands when they fought to disarm Mr Chowdhury as he shouted repeatedly "Allahu Akbar" (God is the greatest).
Mr Chowdhury had claimed the incident outside Buckingham Palace had been an attempt at suicide.
But the prosecution told the court that after he was cleared at the Old Bailey, Mr Chowdhury bragged to undercover officers who had him under surveillance that he had deceived the jury.
He also unwittingly confided in the officers, who were working to earn his trust from January 2019, plans to target busy London tourist attractions, with Madame Tussauds and an open-top tourist bus among the potential targets discussed, prosecutor Duncan Atkinson QC said.
"Believing them to be as sincerely committed as he was, he told them of his devotion to the cause of violent Islamic extremism, the basis for this devotion and the skewed religious beliefs that underpinned it," Mr Atkinson said.
He said Mr Chowdhury was "motivated by dreams of martyrdom for the cause of Islam, and inspired by preachers of hate".
"The object was to unleash death and suffering on non-Muslim members of the public who happened to be present, using a firearm, sword and even a van as part of an attack," he said.
The prosecutor told jurors they could consider Mr Chowdhury's "assertions" to the undercover officers that he was "indeed trying to carry out a terrorist attack in 2017 and that he had deceived the earlier jury that acquitted him of it".
Mr Atkinson added: "Whatever the position in 2017, he was unquestionably preparing for terrorism in 2019."
Mr Atkinson said Mr Chowdhury's sister had "better reason than anyone" to understand what her brother was thinking and wanting to achieve, but she did nothing to stop him.
The prosecution said Mr Chowdhury used his sister's bank account on 10 March 2019 to buy two Red Oak Bokken wooden training swords, which were delivered to their home address.
Mr Chowdhury was also able to buy a replica Glock gun and looked into firearms training, Mr Atkinson said.
He also sought to involve the undercover officers in his firearms-related training and carrying out terrorist attacks, Mr Atkinson added.
In the lead up to the Buckingham Palace incident he had made references on WhatsApp to the "Westminster jihad attacker"' Khalid Masood, who had killed five people in March 2017, and wrote it was "a good way to go".
Mr Chowdhury is charged with one count 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 of disseminating terrorist publications.