Britain's ruling Conservative Party will see its electoral chances enhanced significantly, with 10 more MPs potentially added after boundary changes are introduced for the next general election.
While Parliament will retain a total of 650 members, more constituencies will be created in areas that favour the Tories.
Parts of northern England, Wales and Scotland will lose seats, as they now have fewer voters owing to population shifts. Wales will lose up to eight seats and Scotland three, although both countries have their own devolved assemblies providing a degree of self-government.
The Office for National Statistics on Tuesday released the latest population figures for each constituency, showing some broad differences in voter numbers. For example, in the east London constituency of West Ham there are 98,000 registered voters, compared to 55,000 in Wirral West, near Liverpool.
The UK smallest constituency of Arfon in Wales has even fewer voters, with only 42,000 registered.
The UK's Boundary Commission will examine the numbers in detail and decide where to alter electoral boundaries in time for the next election expected in 2024.
Some electoral experts believe the change is well overdue, with some MPs overwhelmed by constituent queries, while others representing less populated areas have less work to do.
"If you go back to the early 19th century, things were getting very unbalanced with big new towns like Birmingham and Manchester having very few MPs and tiny places that were falling into the sea still having two members each," electoral expert Martin Baker told The National. "By 2020 it was clear that a fair bit of the population had moved away from northern England towards southern England."
Under the Parliamentary Constituencies Act, all 650 areas will be redrawn, with around 73,000 voters each. The last change took place in 2010 based on data from 2000.
However, the changes will adversely affect the Labour Party, which needs to gain 124 seats to form a majority government in the next election.
While the number of London seats will increase by a handful, favouring Labour, the South East is expected to gain seven and the South West three, with both areas strong in Tory voters.
“Although all this is very fair and part of good electoral governance, it will benefit the Conservative Party,” said Mr Baxter, founder of the website Electoral Calculus. “The government is putting it forward with probably two thoughts in their head. One is the right thing to do administratively and secondly it doesn’t do them any harm.
"The key thing is that the decision in the end still rests with the people of the United Kingdom, they get to choose the MPs that go to Westminster and this really just enables their choice to be made more fairly.”
MPs will no longer be able to vote on the current plans, so it will be left to political parties to influence any changes to the electoral map. Many members will attempt to stop their seats disappearing or boundary changes that might result in them losing comfortable majorities – MPs from the same party in neighbouring constituencies might even start lobbying against each other in the interests of self-preservation.
“There won’t be a row as such, but there will be, no question, political manoeuvrings,” said Robert Hayward, a Conservative psephology expert. “The target for the parties is to produce the largest number of seats in a close election. They don’t want massively safe seats.”
Reviews of parliamentary constituencies are carried out by independent boundary commissions. The government said the updated borders would reflect "significant changes in demographics, housebuilding and migration".
A plan to use the boundary changes to reduce the number of MPs from 650 to around 600 has been shelved.
