A young woman was attacked, punched and verbally abused as she tried to protect a runaway police horse blinded by fireworks during last night’s Million Mask March.

Daisy Greenaway, 20, from Harrow, today told of her horror as baying demonstrators spooked the horse into throwing its rider and bolting during violent clashes outside Buckingham Palace.

Anti-capitalism protestors clashed with ranks of police guarding the Victoria Memorial amid a barrage of bottles, traffic cones and fireworks.

Miss Greenaway, a University of Westminster student, had followed the group along The Mall after joining around 3,000 placard-waving activists in Trafalgar Square from 6pm.

She attended the protest to show her support for the anti-austerity campaign and said it was initially peaceful.

She said: “At Buckingham Palace it really took off. A horse ran past shortly followed by the officer who was previously riding him. People threw fireworks.

"When I told them not to hurt horses they said ‘police horses don’t feel’.

“I pulled one masked guy away from a horse who then tried to fight me.

"He punched me and yelled sexist abuse for pushing him away from a frightened horse.”

An officer at the scene told the Standard the horse had been blinded after a masked protester shot the firework directly into its face.

Scotland Yard confirmed an animal had suffered injuries and was returned to the police stables for treatment.

The annual bonfire night protest brought six hours of mayhem to the West End as groups splintered off the designated route down Whitehall to Millbank, sparking pockets of violence across the city centre.

About 50 arrests had been made by midnight, mainly for public order offences.

Three police officers were taken to hospital including the thrown rider.

Sources told the Standard that initial fears of more serious unrest were averted after two coaches taking so-called “Black Bloc” hardcore anarchists were stopped on the motorway en route to Trafalgar Square.

Three hours earlier three men - aged 38, 50 and 55 - carrying knives, gas canisters and lock picks were arrested in a police stop and search.

By 11pm the last 100 protestors who returned to Trafalgar Square after a dispersal order had been served were being held inside a police cordon outside the National Gallery. The last groups were led away to tube and train stations at midnight.

The Met today said its strategy of flooding the streets with hundreds of officers ensured the protest was “mostly peaceful”.

A police car parked in Queen Anne’s Gate, a side street yards from New Scotland Yard, was set alight and its windows smashed.

Another group attempted to disrupt the premiere of the third instalment of the Hunger Games in Leicester Square minutes after stars including Jennifer Lawrence and Julianne Moore had taken the red carpet.

Teaching assistant Jonathan Gomez, 20, from Stratford, said: “They came in wearing V for Vendetta masks, barged people out of the way and were drinking alcohol. Police came and led them away.”

A photographer taking pictures of thugs trying to smash up a £140,000 Aston Martin Vantage in Grosvenor Place suffered a suspected broken arm when the driver pulled off at speed to escape.

Police dog-handlers guarded the entrance to the BBC as some protesters ran up Regent Street, trapping staff and customers in designer stores as they launched fireworks into the air. Other activists ended up in Mayfair, where windows were smashed and bins upturned.

The protest, on Guy Fawkes Night, was one of dozens held worldwide in support of the “hacktivist” collective Anonymous.

Commander BJ Harrington said today: “Officers have been hospitalised, a police horse suffered injuries and a police car was criminally damaged during the course of the protest which is completely unacceptable.

“I praise the professionalism and restraint that officers have shown in the face of hostile provocation and enabled the policing operation to pass without major incidents. We will bring those responsible for the criminality to justice.”