Plans to redraw the political map of Norfolk have been thrown into doubt by deputy prime minister Nick Clegg after a political row between the coalition parties came to a head.

Constituency boundary changes had been proposed for the whole country by the coalition in order, said David Cameron, to equalise the number of voters in each seat; though many also believed the changes would deliver an electoral advantage to the Tories.

But Liberal Democrat leader Mr Clegg yesterday said his MPs would block the proposals after Tory backbenchers scuppered his party's plans to reform the House of Lords.

It means plans to create a new constituency straddling the border of Norfolk and Cambridgeshire will probably never come to pass; a change which could have seen South West Norfolk Conservative MP Liz Truss competing with North East Cambridgeshire's Tory MP Stephen Barclay for a single seat.

Despite having avoided the potential contest, Ms Truss yesterday told the EDP she was disappointed boundary changes were looking unlikely.

She said: 'From the point of view of Norfolk it would have been better to have equal sized seats as the county is under represented compared to some parts of the country.

'Having said that it is early days, we've only just heard the announcement and I think it's too early to say exactly what the implications will be.'

Nick Clegg's announcement yesterday came after weeks of rows over plans to push through reform which would have seen an 80pc elected House of Lords with a membership of 800 falling to 450.

The plans had become all the more important to Lib Dems, after attempts to get another key constitutional reform dissolved with the loss of the referendum on the AV electoral system.

However, a large number of Tory backbenchers fiercely opposed House of Lords reform, refusing to back its passage through Parliament.

Mr Cameron's failure to bring the rebels into line behind the proposals meant Mr Clegg yesterday said the coalition 'contract' had been broken.

The deputy prime minister said: 'My party has held to that contract even when it meant voting for things that we found difficult.'

'But the Conservative party is not honouring the commitment to Lords reform and, as a result, part of our contract has now been broken,' he added.

'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.

'Coalition works on mutual respect. It is a reciprocal arrangement, a two-way street. So I have told the prime minister that when, in due course, parliament votes on boundary changes for the 2015 election I will be instructing my party to oppose them.'

As well as the cross-border Wisbech and Downham Market constituency, the proposed changes would have seen a new Thetford and Swaffham constituency, which would be an amalgamation of parts of the current Mid Norfolk seat and South West Norfolk.

Other parts of South West Norfolk, including Wiggenhall, Tilney St Lawrence and Watlington, would have been absorbed into a new King's Lynn constituency, also taking in all of Henry Bellingham's existing North West Norfolk seat.

The Boundary Commission, tasked to draw up changes, also said alterations were needed to Norwich North, Great Yarmouth and North Norfolk to bring them up to size.

It would have meant Dereham becoming part of a revamped Broadland and Dereham constituency, while Taverham North and South, plus Drayton North and South would leave Broadland to become part of Norwich North.

Elsewhere Fakenham would switch to North Norfolk, while three wards currently in that constituency - Stalham and Sutton, Waterside and Waxham - would move to an extended Great Yarmouth.

North Norfolk MP and Lib Dem minister Norman Lamb said he was 'pretty disgusted' by the way Lords reform has been undermined by some Conservative 'reactionaries'.

He went on: 'If you make a bargain and you can't deliver on that bargain then of course there are consequences. The damage is that we've lost a chance to get rid of a flaw in our democracy. Meanwhile the Conservatives have lost the boundary changes.'

In Suffolk proposed alterations would have left Waveney, Suffolk Coastal, Central Suffolk and North Ipswich untouched. However, four wards would have been removed from the current Bury St Edmunds seat and Newmarket would be merged into a new Newmarket and Ely constituency.

The clash over Lords reform has laid bare a deep rift between the coalition parliamentary parties and has even left a question over whether the government can deliver other parts of its agenda.

However, Mr Lamb added: 'It's time for responsibility on both sides. This has been a bad experience with neither coalition party getting what they wanted.

'But we need to draw a line under this and get back to what is important; fixing the economic problems that came about after 2008.'