A man sparked chaos after rushing from the queue and grabbing the Queen’s coffin as it was lying in state.
Police leapt on the man and dragged him away from the monarch’s casket within seconds of him barging through the crowd to touch it.
He attempted to pull the royal standard flag off Her Majesty’s coffin in the disturbing episode, which saw him arrested.
Mourners watched open-mouthed as the man was restrained by police before being carried out of Westminster Hall.
A Met Police spokesman said: “At 10pm on Friday 16 September officers from the Met’s Parliamentary and Diplomatic Protection Command detained a man in Westminster Hall following a disturbance.
‘He was arrested for an offence under the Public Order Act and is currently in custody.”
A witness told MailOnline : “We saw him (the man) in the queue from the beginning of the queue and throughout the day, he was by himself.
‘When we entered the room we were at the top of the stairs when we saw the incident. A lady screamed as it happened it was quite unnerving. Although he was detained and people kept calm and carried on.”
One mourner in the queue told The Sun they heard a shriek and thought someone had fainted.
A witness told MailOnline : “We saw him (the man) in the queue from the beginning of the queue and throughout the day, he was by himself.
‘When we entered the room we were at the top of the stairs when we saw the incident. A lady screamed as it happened it was quite unnerving. Although he was detained and people kept calm and carried on.”
One mourner in the queue told The Sun they heard a shriek and thought someone had fainted.
However, they then saw that a man was trying to pull the royal standard off the coffin.
The witness said: “They picked up the bottom and wafted it, almost to see what was underneath. It happened so fast.”
The mourner added that it was “extremely upsetting” to see someone “disrespect” Her Majesty.
Another witness, Tracey Holland, said the man pushed her seven-year-old niece Darcy out of the way as he rushed the casket.
She added: “A person decided they were going to push my seven-year-old niece out the way, run up to the coffin, lift up the standard and try to do I don’t know what. The police had him within two seconds.
“(It was) terrible, absolutely terrible, so disrespectful and unbelievable – and this poor little seven-year-old child, this is her lasting memory of the Queen.”
One mourner said people were left “hysterically crying” and “shaking” after the distressing episode.
A spokesperson for the the UK Parliament, said: “We’re aware of an incident in Westminster Hall, in which a member of the public moved out of the queue and towards the Catafalque.
“They have now been removed from the Hall and the queue restarted.”
Live streams of the Queen’s coffin cut for around 15 minutes during the incident.
When the BBC live stream returned the royal standard appeared to have been moved.
It comes after the queue to see the Queen lying-in-state was shut overnight after the waiting time hit the maximum length.
People wishing to pay their final respects to Her Majesty in Westminster Hall have been filing past her coffin since Wednesday, with the mammoth line continuing to grow.
The Department for Digital, Culture, Media and Sport (DCMS) has now confirmed entry to the queue to see the Queen has been paused for “at least” six hours.
Officials earlier stopped people from entering the queue, causing a crowd to form around the entrance as people begged to be let in.
In an update shared at 1.15am on Saturday, the DCMS said: “The queue is near total capacity with a wait time of at least 25 hours. Please do not travel to join the queue. Check back for updates in the morning.”
The DCMS said on Friday that access to the queue would resume at midday on Saturday.