Nick Clegg joins in at last to attack 'dinosaurs who are against AV'

Nick Clegg came out fighting today as he sought to turn the tide in favour of voting reform.

The Deputy Prime Minister attacked Labour and Conservative "dinosaurs" opposing a switch to the alternative vote. He also attacked David Cameron and Ed Miliband over their tactics on rival sides of the campaign.

Mr Clegg has been largely absent from the Yes campaign, which has sought to distance itself from a politician it regards as toxic. That has made him a figure of fun for the No supporters.

Today the Liberal Democrat leader accused the No campaign of negative tactics, saying: "When the vested interests of the old, tired establishment of politics and the media are so opposed to a reform, turning so personal about it, you know there is something worth fighting for.

"It is the attack on people working together for the national good that is so dismal.

"It is a desperate attempt to defend the indefensible - the old politics of tribalism backed by dinosaurs on all sides of the political spectrum."

Mr Clegg sought to defend his party's role in the Coalition during a speech at the Institute for Public Policy Research think tank, which came as polls showed growing opposition to AV.

Countering claims that the Liberal Democrats abandoned their principles to govern with the Tories, he said: "Compromise is not betrayal."

And in what will be seen as an attack on Ed Miliband, he added: "You can't claim to stand for a new kind of politics, for a new kind of pluralism, and then vilify those who try to practise it."

Mr Clegg hit back at claims from No campaigners that AV would lead to more coalitions and therefore broken promises, and argued AV would be good for democracy, ensuring MPs have majority support.

His speech came as new research showed half of the over-50s are No supporters, and polling data predicted Liberal Democrats will lose hundreds of seats in local council elections on May 5, the same day as the AV referendum.