Tory ministers have been warned millions of voters are ‘missing’ from the system as MPs prepare to pass a new law on boundary changes.
MPs will tonight hold their final vote on a Bill which will trigger a review of Westminster’s constituency boundaries.
The review – due to report back in 2023 after years of failed attempts – is designed to make Parliament fairer by making each MP’s seat a similar size.
But campaigners say around 9million people will be missing from the system – many of them in the poorest and most deprived seats.
That is because they are not on the electoral roll, which is being frozen in time as it was on March 1 this year and used to work out the new system.
That means when the seat sizes are doled out, many will have “hidden” potential voters who will be under-represented – because their MP will end up having far more constituents than they thought.
Meanwhile, well-heeled areas where most people are registered will have more MPs to share between them.
The Electoral Reform Society has called for the seats to be based on a system of automatic voter registration to make it fairer.
The Lib Dems will tonight launch a last-ditch bid to change the law.
The party is putting down an amendment which would end the reliance on the electoral roll and use all “potential” voters living in each seat instead.
Labour is still considering whether to back the amendment, but it is doomed to fail as the Tories have an 80-seat majority.
Wendy Chamberlain, the party’s spokeswoman on political reform, said: “The Government claims to be reforming the electoral boundaries to improve democratic representation here in the UK.
“But when their definition of the electorate ignores 9 million individuals who are eligible to vote, then they have serious questions to answer.
“Those who are not on the electoral register are often those underrepresented, disaffected or from sections of our society that are harder to reach.
“We cannot allow them to be disadvantaged further, by being treated as if they don’t exist as these new boundaries are drawn up.”
Darren Hughes, Chief Executive of the ERS, added: “The fact that seat boundaries are carved up on the basis of Britain’s incomplete electoral roll means those in areas with lower registration rates lose out.
“It’s an electoral iniquity that must be tackled now.
“This is a real problem given that those less likely to be on the register are typically younger, from lower-income groups, renters, and people of colour.”
Labour will also put down an amendment to the Parliamentary Constituencies Bill, to allow more variation between the size of each seat.
The party wants there to be a 7.5% maximum difference between each seat size, rather than 5% as it is now.
Shadow Cabinet Office Minister Cat Smith said the law as it’s drawn up will “split communities” because there is so little room for manouevre.
Tonight’s Bill will kick-start a brand new Boundary Review after the previous £5m, long-delayed plan was ditched in March.
Plans to cut the number of MPs from 650 to 600 had been proposed in 2016 after the review before that one had to be abandoned in 2013.
But the changes prompted a political bunfight as scores of MPs were pitched into a battle for survival with their nieghbours.
And Labour said the carve-up was a Tory “power grab” because it left out a surge of young voters for the EU referendum and 2017 election.
The Tories have now come forward with fresh proposals which will keep the number of MPs at 650, but make their seat sizes more equal.
Four Boundary Commissions for the four nations of the UK will hold a review to work out where the boundaries should go, starting in 2021.