The "Hackney Heroine" - who confronted rioters in the nation's capital in 2011 - was turned away from the queue for the Queen's lying in state.
Pauline Pearce was one of many mourners who waited in line to see the monarch's coffin only to find out they could not enter Westminster Hall.
Ms Pearce queued up for seven hours in the hope of being allowed in to pay her respects to Her Majesty.
She said she and others were given "false hope" when they queued up without wristbands.
Ms Pearce said: "We were sent from one point to another and living off the false hope that they might let us in.
"At one point they said they were going to open the gates, then suddenly they didn't. There was no empathy at all from the organisers."
Ms Pearce shot to fame as the "Hackney heroine" after she was filmed confronting rioters in 2011.
Another mourner, Fiona Harper, 60, said organisation of the last night of queuing was characterised by "inaptitude" with confusion about where wristbands were to be handed out.
Ms Harper said: "The problem was that we were all led to believe that you picked up your wristband at the end of the queue. So, we were querying for an hour and a half before they told us there were no more wristbands."
Meanwhile, London's City Hall said public viewing areas for the procession of the Queen's coffin from Westminster Abbey to Wellington Arch were full.
A statement on Twitter said: "All procession viewing areas are now full. There is no entry to any new arrivals. Please follow the advice of stewards and police.
"If you are in the area or about to arrive, use the dedicated walking route to Hyde Park to watch Her Majesty The Queen's state funeral and procession."
It comes after the queue to view the Queen lying in state finally closed, with mourners told to avoid joining the line.
The Department for Digital, Culture, Media and Sport confirmed the queue had been closed at around 10.45pm on Sunday.
Brits started joining the mammoth queue, which has become an internet sensation in recent days, on Monday.
It stretched for more than five miles at its peak, with estimated waiting times reaching over 25 hours on Saturday.
Announcing the closure, the DCMS tweeted: "The queue to attend Her Majesty The Queen's Lying-in-State is at final capacity and is now closed to new entrants.
"Please do not attempt to join the queue Stewards will manage those already nearby Thank you for your understanding".
The police are now executing the largest security operation in British history as they protect the Queen's funeral.
A ring of steel has been set up around Westminster Abbey.
Police snipers are lining the rooftops as thousands of officers and members of the armed forces stand guard in the capital today.
More than 10,000 police officers and staff have been pulled in to work the funeral and every force in the UK has contributed, including the Police Service of Northern Ireland.
