The exhaustion of a long-fought election campaign and a sleepless Thursday was not enough to keep a parliamentary hopeful from protesting outside Downing Street.

Anti-government campaigner Jonathan Bigger, who stood as a Class War candidate in the Croydon South constituency and polled 65 votes, was at the protest on Saturday and said it was just the beginning.

He said: "At the declaration on Friday morning I said people need to mobilise as quickly as possible and I’m glad that people did.

"What I want is five years of rebellion, five years of civil disobedience.

"Every time the Tories try to do something with their Government we will protest against it.

"We are not going to give in, we are not going to give up. We are not going to stop fighting.

"The £12bn cuts will cause widespread devastation. We will see more suicides, NHS privatisation and more foodbanks."

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At the protest 12 people were arrested on suspicion of violent disorder and three for assault on police.

Two police officers needed hospital treatment, one for a suspected dislocated shoulder and the other for a cut lip.

Mr Bigger said he saw scuffles and claimed the only violence he saw was by officers.

During the protest the Women of World War II monument on Whitehall was defaced.

Mr Bigger said: "I did not see that happen and I’m fairly sure that the Government can afford some cleaning products to get rid of the graffiti."

Metropolitan Police spokesman Acting Commander Colin Morgan said: "We respect the right of people to protest peacefully, while we must also balance the need for Londoners and visitors to go about their business - and for events such as this weekend's VE Day celebrations to be held safely.

"We carefully assess the intelligence and information available to us and we put in place the most appropriate policing operation, which will often include having officers available on standby to respond rapidly to disorder."