DAVID CAMERON’S hopes of a Conservative majority in 2015 suffered a massive blow yesterday, when a planned scrapping of 50 MPs – including three seats in the North-East – was dramatically killed off.

The Liberal Democrats announced they would vote against a redrawing of Britain’s electoral map, one that was expected to hand the Tories a gain of up to 20 seats at the next General Election.

The move – in revenge for Conservative backbenchers blocking House of Lords reform – plunges the Coalition into a fresh crisis, after ministers insisted the existing boundaries handed Labour an unfair advantage. Without the shake-up, the Conservatives will need to win by up to 11 points in 2015, in order to win a Commons majority. The party is currently nine points behind Labour.

In the North-East, the scrapping of 50 seats would have mean the loss of one in the south of the region and two in Tyne and Wear, to create nearequal constituencies of between 72,810 and 80,473 voters.

Some election experts had predicted the Tories had a chance of winning three redrawn seats, those of Sedgefield and Yarm , Darlington and Middlesbrough South and Guisborough .

Last night, Pat Glass, the North West Durham MP – faced with a proposed new Consett and Barnard Castle seat, stretching 60 miles, from Hadrian’s Wall to the Yorkshire border – welcomed a Uturn that made “geographical sense”.

But the Labour MP also predicted the announcement was the “beginning of the end of the Coalition”.

Mrs Glass said: “On a personal level I’m very pleased, because my constituency will remain and that’s what local people wanted. It makes geographical sense.”

However in Westminster, the Conservatives – behind in the polls – have reason to be as fearful of an early election as the Lib Dems.

The Prime Minister still plans to press ahead with the vote to implement the cutting of 50 seats – late next year – although the parliamentary arithmetic would appear to make it unwinnable.

Mr Clegg insisted the Coalition remained focused on the “urgent task” of rescuing the economy, describing the abandoning of boundary reforms as an “amendment to the contract”.

He told a press conference: “Clearly, I cannot permit a situation where Conservative rebels can pick and choose the parts of the contract they like, while Liberal Democrat MPs are bound to the entire agreement.”

A compromise – a referendum on Lords reform in 2015, with both the boundary changes and Lords’ elections deferred until 2020 – had been rejected by Mr Cameron, the deputy prime minister said.

For the Tories, Culture Secretary Jeremy Hunt said Mr Clegg’s announcement was disappointing, but the two parties remained united on “sort