When 81 Conservative MPs defied David Cameron's will last October in a vote over an EU referendum it was a chilling warning of how tough his rule might be.

The vote showed there was a sizable number of Conservatives, many from the 2010 intake, who did not fear the whips enough to shy away from challenging his leadership.

But it also demonstrated that many backbenchers did not feel that right-of-centre views were being adequately heeded by Mr Cameron.

That frustration was never going to be easy to contain in a coalition with a Liberal Democrat party which has the power to block policies they feel unpalatable.

Now after months of Tory backbenchers complaining that Lib Dems have been 'punching above their weight' in the coalition, many appear to be ready to prove their point.

Their chosen political battle-field is reform of the House of Lords; an issue the success of which is not only very close to Lib Dem hearts, but also central to party leader Nick Clegg's ability to justify staying in the coalition.

Under the plans he has brought forward, the new Lords would be an 80pc elected chamber with a slimmed down membership falling from the current 800 to 450.

Hereditary peers would be completely removed and the first elected members introduced in tranches of 120 at each of the next three general elections, with the process of change completed by 2025.

Meanwhile ninety non-elected members will be given seats by a statutory Appointments Commission on a non-party basis.

Elected members would serve for a single 15-year non-renewable term and rather than a salary would instead receive �300 for each day they attend, on which they would be taxed.

The Tory rebels claim they have up to 100 amongst their number which, if Labour also voted against the proposals, would be enough to inflict a defeat on the government. That would not just be embarrassing, but potentially fatal to the Liberal Conservative coalition.

The Lib Dem MP for North Norfolk Norman Lamb, also a business minister, said: 'We are voting to modernise our democracy so that the people that vote in new laws are elected by the people and not appointed by the prime minister.

'It will be a great achievement for this coalition government, and for the Tories as well as Lib Dems, to have finally acted to modernise our democracy after hundreds of years.'

Other Norfolk ministers - Norwich North MP Chloe Smith, North West Norfolk MP Henry Bellingham and Broadland MP Keith Simpson, who is Foreign Secretary William Hague's parliamentary assistant - are lining up behind Mr Cameron and Mr Clegg.

Meanwhile Yarmouth MP Brandon Lewis, Mid Norfolk MP George Freeman, South West Norfolk MP Liz Truss and Waveney MP Peter Aldous have all also signalled that they will back the proposals.

Suffolk Coastal MP Therese Coffey has said she would like to see the reforms altered before she falls in behind the government.

Criticism of the proposals has centred around claims that the public are disinterested in constitutional reform, that changes will cost much needed money, that the public do not want more elected politicians and that the reforms will have unintended legal and political consequences.

Baroness Shephard of Northwold, the Conservative former cabinet minister, has even argued that a new elected Lords chamber would be able to challenge the decisions of the House of Commons in the courts.

South Norfolk MP Richard Bacon, who suggested he would probably vote with the government too, also said he could foresee situations in which the Lords would challenge the 'primacy' of the Commons.

'They will use more willingly the powers that they have because, having been elected, they will rightly feel that they have a mandate,' he said.

'The idea that the government of the day will simply just be able to control them is fanciful. Personally I would like to see the Lords untouched.

'But it seems to me that the long term interests of the country require us to keep the coalition going. Lords reform is a bit of a distraction at the moment but it may be just one of those things that we have to swallow.'

This week will see rebels going door to door down the corridors of Westminster in a bid to boost their numbers, while the government's whips will also swing into action to ensure Tory MPs vote the right way.

It helps the whips that a reshuffle is expected soon, focussing the loyalty of many of those ambitious Tory MPs who are gunning for a position in government.

Last week a spokesman for David Cameron commented that any Tory MP that voted against Lords reform would be making 'an interesting career move'.

It all means that when the vote finally comes around next week the government will most likely win, but even that may not be enough to deliver the reforms the Lib Dems desire.

If there is a sizable rebellion, even if it is not big enough to rob the government of its majority, then Baroness Shephard has suggested the House of Lords will become emboldened to block the reforms with endless delaying tactics.

'It would be possible to prolong debate so that there was no other room for other legislation. But we would not want to do that if the House of Commons states firmly that they back it,' said the baroness, who has led opposition to the reforms amongst peers.

'But if there is a significant rebellion then it will make the Lords more willing to do what they can to attack the reforms.'

The second reading of the proposed reforms, involving a debate followed by a vote, will take place in the House of Commons on July 9 and 10.