Tory plans to redraw electoral map could hit Lib Dem seats hardest

The Liberal Democrats face losing up to a quarter of their seats when a Tory-imposed plan to redraw the entire electoral map comes into force from September, figures seen by the Guardian suggest.

The boundary review to equalise constituencies and reduce their number by 50, agreed by Nick Clegg in exchange for the AV referendum in the coalition agreement, is threatening the biggest upheaval to the Commons of this parliament. MPs have been warned that almost no seat is safe.

The issue could force a mutiny in the coalition amid mounting evidence that the Liberal Democrats will fare far worse than predicted and with David Cameron facing further tensions with his backbenchers, some of whom are certain to lose their seats.

The four Boundary Commissions of England, Scotland, Wales and Northern Ireland are preparing to announce the new electoral map in September.

But the most detailed analysis yet of what those new seats might look like, conducted by academics based at Liverpool University and published by the Guardian, suggests the Liberal Democrats will lose the greatest proportion of their seats. Fourteen out of 57 could be wiped off the electoral map.

The Tories have long argued for the changes to redress what they see as an imbalance that has helped Labour win elections on a lower share of the vote. But the analysis suggests that instead it is the Liberal Democrats who will bear the brunt of the reforms.

"The Liberal Democrats clearly did not know what they were agreeing to. It was extremely naive. It's like turkeys voting for Christmas," one Labour source said.

Lewis Baston of Democratic Audit, a research group working from Liverpool University, has devised a model of the new map based on the guidelines set out by the legislation behind the reforms. In his version, the Tories would lose 16 seats – 5.2% of their total; Labour would lose 17 – 6.6%; and the Liberal Democrats a crippling 14 – 24.6%. Ministers including Norman Baker, Sarah Teather, Andrew Stunell and Grant Shapps would be among those most vulnerable.

Baston said: "The Liberal Democrats are likely to lose out more than the other main parties because their seats are yellow islands in a sea of red or blue; changing the boundaries is more likely to bring in hostile territories, their majorities tend to be smaller than Labour or Conservative MPs and their Lib Dems trade a lot on incumbency and constituency service. That is disrupted by a boundary review."

But he said the Tories had also overestimated any advantage the reforms could present them with. "They put too much faith in this, it will unsettle MPs of every party, all over the place."

MPs who potentially face a fight for the same seat include the chancellor, George Osborne, and the chair of the Conservative 1922 backbench committee in parliament, Graham Brady, as well as the Liberal Democrat chief secretary to the Treasury, Danny Alexander, and the popular former leader of his party, Charles Kennedy.

Some senior sources in the Liberal Democrat and Tory parties disputed the findings saying they are markedly different from previous projections. Other predictions made by the parties themselves dispute the extent of the problem for the Liberal Democrats but back up the theory that it fails to extend the Tory lead over Labour. Some respected psephologists have argued that the boundary changes will not dramatically advantage the Conservatives.

Lord Tyler, the Liberal Democrat constitutional affairs spokesman in the Lords, said: "The penny hasn't dropped in Downing Street about the effect this will have on the backbenches, but the penny has certainly dropped in local constituency offices. There are MPs asking why this is being rushed, why it has to be necessary at this stage."

An account of an internal briefing with the parties reveals that the Boundary Commission for England has issued a warning that no seat is entirely safe from change. It says: "He [the deputy chairman] took the opportunity to emphasise again that any assumption that an existing seat … would automatically remain untouched was not correct."

Overall, 50 seats will be abolished. It has already been confirmed that Wales, which has historically small constituencies, will lose 10, the north-west will lose seven and London and the West Midlands will lose five each. Labour loses the most because it dominates inner cities where constituencies often have fewer voters.

Where boundaries change, MPs of the same party will also be fighting one another for reselection. Marginal seats could be made even more marginal while dozens of seats will change hands as boundaries alter the political composition of the electorate.

The new seats will be announced from 6 September, making for a summer of uncertainty for MPs. A lengthy consultation will follow in which the parties can make representations to challenge decisions. The new map will be subject to a vote in both houses of parliament, creating a point of rebellion in 2013. One Tory said: "The question is, if you're a Lib Dem and there is a Labour rebellion, do you join with them in opposing this? You rely on incumbency – being known to your patch – and then not only do you lose that but, by being in government, you're more unpopular than you've ever been. Their party leadership may have decided they can't ask their troopers to vote it through."

The Conservatives are ploughing substantial resources into preparing for the reforms. Roger Pratt, a political strategist with 40 years' experience in the party, has been leading a boundary review group since last summer. It has made its own calculations of what the Boundary Commission is going to do and Pratt has been briefing MPs one-to-one and on a regional basis advising them of the changes.

Cameron told a private meeting of his MPs some months back that no one would lose out – suggesting that they would either be given the seat of a retiring MP or possibly be elevated to the Lords.

It is understood the Conservative party is also prepared to make counterproposals, should it disagree with the outcome in a consultation process in the autumn.

Labour has its own group, led by its chief strategist Greg Cook – known as "Mystic Greg" for his ability to predict election results. It has been drawing up rules to help resolve territorial disputes between competing MPs. Labour MPs will be able to lay claim to a new seat if it includes substantial numbers of their current constituents.

"There will be needless disruption," the Labour source said. "There will be some silly outcomes – some local boroughs will end up overlapping with others and it will be ridiculous.

"They have taken away the rule not to cross London boroughs. It will be confusing for MPs who may in future find they are dealing with as many as seven local councils when trying to secure a win for a constituent."

The Liberal Democrats have sent delegations to meetings with the commission but, struggling with funding cuts to their party HQ, their preparation is less comprehensive.