Plans to redraw the country's political map which would have seen Norwich North constituency transformed, have been thrown into doubt by deputy prime minister Nick Clegg.

Constituency boundary changes had been proposed for the whole country by the coalition in order, David Cameron said, to equalize 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.

Mr Cameron's failure to bring rebels into line behind the Lords 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.'

The boundary changes would have seen Taverham North and South, plus Drayton North and South leaving the current Broadland seat to become part of Norwich North.

The constituency's Tory MP Chloe Smith said: 'I look forward to serving Norwich North and contesting the constituency at the next election whatever its shape.'

The Norwich South seat of Lib Dem MP Simon Wright, unavailable for comment yesterday, would have remained unchanged by the boundary proposals.

But North Norfolk MP and Lib Dem minister Norman Lamb said: 'We need to draw a line under this and get back to what is important; fixing the economic problems that came about after 2008.'