By Alex Stevenson Follow @alex__stevenson
Britain could face more "social disturbance and dislocation" if Westminster parties continue to ignore the views of ordinary people, the director of the People's Pledge campaign has told politics.co.uk.
Mark Seddon, whose organisation is calling for a referendum on Britain's membership of the European Union, linked this summer's riots to frustration with the UK's "increasingly unrepresentative" political parties.
He predicted Britain will see more racism and xenophobia as the eurozone crisis progresses.
Over two-thirds of members of the public would like to be given a vote on Britain's continuing involvement in the EU, according to a recent Guardian/ICM poll.
But the Conservatives, Liberal Democrat and Labour parties all imposed a three-line whip on their MPs when a motion proposing a referendum on Europe was put before the Commons.
"For quite some time a lot of people have been very concerned about the democratic deficit - the fact that our political parties are increasingly unrepresentative in many ways," Mr Seddon said in an interview for politics.co.uk's weekly podcast.
"They don't have as many members, they've become centralised control machines. People are switched off. They don't like the technocratic Westminster classes. They want people to stand up and say what they think.
"I think if this kind of democratic denial continues, there will be even more disillusion, and that's dangerous."
Mr Seddon made clear he believes this summer's riots were not motivated by frustrations over Europe. But he suggested political parties' failure to address the demands of the public would only contribute to causing more social unrest.
"If they feel they no longer have a say, they will resort to extremes," he added.
"And when you see one million youngsters unemployed, and a feeling of not knowing what's going to happen next, it's a very dangerous situation."
Unemployment figures released this week showed 1.02 million 16- to 24-year-olds are now out of work for the first time ever.
German commentators fear David Cameron will deploy harsh rhetoric in today's talks with chancellor Angela Merkel as a result of the unemployment situation in Britain. More people are out of work in the UK than at any time since 1994.
"There is an atavistic nationalism which is very dangerous, small, isolationist," Mr Seddon commented.
"In a way you can understand where some of this thinking is coming from, but it by no means provides the answers for the situation that we're in. I do not think the British political class has got a grip on it."
Mr Seddon, a former editor of the left-wing Tribune newspaper, is particularly frustrated with the Labour party's refusal to embrace calls for a referendum.
He suggested a shift in attitude by Ed Miliband would be rewarded in the opinion polls, as the one person who cannot allow a referendum is the prime minister.
"To my mind, the Labour party under Ed Miliband could argue for Britain remaining in the EU, but it could say we've got to keep our distance and we're not joining the eurozone, and we're going to find other ways of cooperating," he said.
"I think Ed Miliband's ratings would zoom up and the situation would be transformed."