Tony Blair joined Liberal Democrat leader Charles Kennedy yesterday to urge the North-East to vote Yes to a regional assembly in an historic outbreak of political unity.

Speaking on a balcony overlooking the River Tees, Mr Blair said: "We both think bringing regional government to the North-East is a good idea."

Exchanges between the two men across the House of Commons have become increasingly angry recently over the war in Iraq, and only weeks ago the two parties fought a bitter by-election in Hartlepool.

But yesterday, at McQuays restaurant on the Riverside at Stockton, it was all sweetness and smiles as the leaders shared a platform for the first time in four years.

"The fact that we can agree on this should really underscore that this must be a substantially important proposal if we are willing to set aside the highly competitive instincts that exist between us," said Mr Kennedy.

"The principle at stake is too important for party politics because if there is not to be a North-East Assembly it will be a loss for all the political participants of whatever persuasion, and, more importantly, for the people it will be a lost opportunity.

"People should seize the opportunity. I believe where the North-East leads, you will soon find other parts of England will want to follow."

Mr Blair, who voted Yes yesterday morning, said: "Scotland got devolution, Wales got devolution, London has its own government.

"You ask people in those places, would they like that taken away from them now, and they would say no.

"We are often claiming in the North-East that we tend to get left out of certain parts of the decision-making process. This gives us the chance to make the decisions here for ourselves."

When Mr Blair won the 1997 General Election, there was a close relationship between him and the then LibDem leader Paddy Ashdown. Mr Kennedy took over in 1999, and shared a platform with Mr Blair, and Conservatives Ken Clarke and Michael Heseltine, in 2000 to promote Britain in Europe.

Since then, the parties have grown apart, with the LibDems' opposition to the war in Iraq driving a real wedge between them.

"Personally, I get on with him very well," said Mr Kennedy. "We have known each other since 1983 when we were elected and he was a guest at our wedding a couple of years ago."

Yesterday's meeting was a last-minute arrangement. Both men were due in the North-East - Mr Kennedy in Newcastle and Mr Blair in Shildon - and it wasn't until Thursday evening that agreement was reached and their itineraries rescheduled.

The meeting ties Mr Blair to the referendum result. Until yesterday, he had been a peripheral figure in the campaign and would have been able to distance himself from an embarrassing No vote.

"I just think it is going to make a lot of sense given it (the assembly) is going to be handling hundreds of millions of pounds and instead of those decisions being made in Whitehall, we will get them taken in the region," said the Prime Minister whose Sedgefield constituency would be covered by an assembly.

The double-headed meeting was part of a Labour blitz with the Health Secretary John Reid in Newcastle, Sports Minister Richard Caborn in Chester-le-Street and Welsh leader Rhodri Morgan in Sunderland.

In the face of such an assault, the No campaign decided for one day only not to compete for the headlines and did not organise any rival events.

Bishop Auckland businessman John Elliott, chairman of North East Says No, said: "The faltering Yes campaign is getting desperate, which is why it has deployed its politicians today.

"The people of the North-East should ignore the spin and look at what the politicians are actually offering. All we've heard from them is just more meaningless statements.

"They are trying to sell people an expensive white elephant which will raise council tax but which will not have the powers to do any good. It would not have the power to employ even one extra nurse, doctor, teacher or police officer."