Conservatives accused of trying to rig the election system as proposed boundary changes hit Labour

But Theresa May also faces a backlash from Tory MPs whose seats are at risk

The Conservatives have been accused of trying to rig the UK’s electoral system after a Tory-commissioned review threatened to strip an estimated 23 seats from Labour.

Jeremy Corbyn’s party branded the proposals “unfair, undemocratic and unacceptable”, while campaigners claimed they were based on flawed data and would “skew” democracy.

The Labour Leader’s own North London seat is set to be axed, while leading moderates such as Yvette Cooper and Chuka Umunna faced changes that could leave them vulnerable to de-selection.

But doubt has been cast over whether the plans will ever come into force, after they also put a higher-than-expected number of Tory seats at risk.

Theresa May’s MPs were said to be “shocked” by potential Conservative losses which could rise to 17 – the exact number of her Commons majority.

Among prominent party figures at risk are ex-chancellor George Osborne and top cabinet Brexit backers David Davis and Priti Patel.

David Cameron tasked the Boundary Commission to reduce the number of MPs and “equalise” the registered voters in every remaining constituency.

Ministers claim the drop from 650 to 600 MPs will save taxpayers £66m over five years. But it is the political, not the financial impact, causing waves.

The changes are likely to hit Labour hardest, with more seats abolished or merged in strongholds like London, Wales, the North-East and North-West than in Tory-dominated shires. The figures for how the parties will fare under the new boundaries come from estimates by the Labour party.

Mr Corbyn said he was unhappy about the changes, which will now be consulted on, but "very confident" about the future. Despite the abolition of his seat, it is unlikely he would not be selected in the new Finsbury Park & Stoke Newington constituency largely formed from his current North Islington base.

But Shadow health secretary Diane Abbott, a leading Corbyn-backer, could be pitched into a selection battle with Blairite MP Meg Hillier in North London as another new seat contained large parts of their existing patches.

Big Labour names like Streatham MP Mr Umunna, Normanton MP Yvette Cooper and Stoke Central MP Tristram Hunt, all appeared to be facing a big enough change in their seats to mean they may have to undergo a selection battle. That could mean large numbers of new Corbyn-backing members having a say in their futures.

Labour shadow minister Jon Ashworth said the plans are “unfair, undemocratic and unacceptable".

He added: “These changes are not about fairness to voters, they are about what is best for the Tory Party and they must not go ahead.

“The Commission must rethink and ensure that no elector loses out.”

Both the Greens and Ukip faced potentially losing their only MP under the changes. The Liberal Democrats claimed they may retain all those they currently held.

But while Labour losses were expected, not many MPs foresaw the impact on Tory seats. Boris Johnson’s Uxbridge and South Ruislip patch will be substantially redrawn, but the Foreign Secretary appears well-placed to secure the Conservative nomination for the seat taking its place.

Brexit Secretary David Davis is not as lucky, with his Haltemprice & Howden constituency in East Yorkshire cut in two, while International Development Secretary Priti Patel – another prominent Brexiteer – also faced big changes.

Conservative chairman Sir Patrick McLoughlin said the party would follow a policy of "no colleague left behind" to minimise the disruption to sitting MPs.

He added: “Boundaries should be drawn up in an impartial and independent way so I welcome the Boundary Commission’s proposals to implement Parliament’s instruction to ensure equally-sized constituencies. Without these reforms, MPs could end up representing constituencies based on data that is over 20 years old."

One Conservative source told The Independent that MPs at risk of being dumped would be offered sweetener jobs outside Parliament to ensure a smooth transition.

But a Tory backbencher said: “Colleagues are shocked, there are a number of outcomes not expected.

“There are a number of people unhappy now, who were not unhappy the last time changes were suggested. Frankly, I’m not convinced this is ever going to happen.”

Another noted that the Maidenhead seat of Mrs May remains as it is, while Chancellor Philip Hammond's Runnymede and Weybridge is also largely unchanged.

The Electoral Reform Society slammed the changes, pointing out that they were based on numbers of registered voters from December 2015, despite some two million having registered since then. Many of the new voters have signed up in Labour held areas.

Chief Executive Katie Ghose claimed that if up-to-date figures had been used some areas would need an extra MP to adequately represent them. She also argued that the seats should be based on the actual population in an area rather than registered voters.

She said: “Areas with the lowest levels of registration are often those that already have the least voice in politics.

“Young people, some ethnic minority groups and those in the private rented sector are all less likely to register to vote than others. That makes many of them effectively cut out of the new political map.”