Crowds of “gasping and screaming” mourners saw a man step from the queue of well-wishers waiting to pay their respects to the Queen and grab the flag draped over her coffin, a court has heard.

Muhammad Khan, 28, was quickly taken to the ground by police officers near the coffin and mourners were “clearly anguished” by the scene while the Queen was lying in state, London’s Westminster Magistrates’ Court has heard.

Khan was sent to receive treatment at a mental health facility by district judge Louisa Cieciora after she found his actions had caused distress to members of the public who witnessed the scene.

Khan, of Limehouse, east London, was charged with an offence under Section 4A of the Public Order Act, which alleges he acted with intent to cause a person or persons unknown harassment, alarm or distress.

The court was told at a previous hearing that doctors had assessed Khan as not fit to take part in proceedings and said he was suffering from delusions.

Khan had left the queue in Westminster Hall on September 16 at approximately 9.45pm. The live feed briefly cut away.

He was seen by officers to approach the coffin. He stepped off the carpet in the direction of the catafalque and then grabbed hold of the Royal Standard draped over the coffin before quickly being detained and arrested.

Pc Lynsey McMenemy, together with Pc Jordan Godfrey, grappled with Khan and all three fell to the ground.

Pc McMenemy said members of the public “gasped” and were “clearly anguished”. He added that he “understood” why the mourners felt that way.

The behaviour (Khan) displayed clearly caused harassment and alarm to the members of the public who were paying their respects to the Queen

Other officers arrived after being alerted by the “gasping and screaming” mourners, the court heard.

After being tackled to the ground and as he was later being removed from the scene, Khan told one officer he “wanted to see if she was really dead”, the court heard.

The judge said she was satisfied that the distress experienced by the nearby mourners was “as a result of Mr Khan’s actions” and not due to the arrest by the officers.

She said the catafalque stood a significant distance away from the people filing through Westminster Hall.

In approaching the catafalque, Mr Khan’s actions would have been noticed by members of the public “most of whom would have been looking at the coffin and who were there to pay their respects”, the judge said.

She added that they would have seen him grab the Royal Standard and “it is that act that would have prompted the gasps and distress that Pc McMenemy heard”.

The judge said she was satisfied, following assessment by two doctors, that Mr Khan was suffering from a mental disorder and should be detained in hospital care where he could be given appropriate treatment.

She told him: “You will be taken to the Tower Hamlets Centre for Mental Health. How long you stay in hospital will depend on your treatment and will depend on your doctors.”

Earlier, prosecutor Adrita Ahmed said that a number of police officers and senior doorkeepers at the House of Commons who responded to the incident had seen Khan step towards the catafalque before he was “quickly taken to the ground”.

She said: “The behaviour he displayed clearly caused harassment and alarm to the members of the public who were paying their respects to the Queen.”

She said that two senior doorkeepers heard “loud screams from the public throughout the incident”.

Rakesh Bhasin, defending, said: “The height of the Crown’s case is that there was screaming and gasps. As you have heard, the incident lasted a matter of seconds. The first officer to see Mr Khan saw him and took him to the ground within a matter of seconds.”

He suggested that the other officers who arrived at the scene soon after had heard screams or gasps but this could not clearly have been caused by Mr Khan’s actions as opposed to his arrest.