The UK Government has agreed to protect the Ynys Môn constituency from what is expected to be the most radical shake-up of Welsh parliamentary seats in more than a century. Under the plans, the tradition of Wales having constituencies with smaller electorates than English seats will be ended, cutting the number of Welsh MPs from 40 to about 32.

Every MP, from all parts of the UK, will represent about 70,000 voters. Until now, there were to be just four exceptions, two Scottish island constituencies and two seats on the Isle of Wight. Previous arguments to include Ynys Môn, which has about 52,000 voters, were rejected on the grounds that it is linked to the mainland by two bridges.

It's an argument that's continued for nearly 10 years, since the Conservative-Liberal Democrat coalition government first attempted to equalise the size of constituencies. Two boundary commission reports, both adding the Bangor area to Anglesey, weren't implemented because of wider opposition at Westminster to the government's intention to cut the total number of MPs from 650 to 600.

That idea has been abandoned but until now it looked as if the island constituency would be abolished, having elected an MP since the reign of King Henry VIII. The government climbed down at a meeting of a Westminster committee examining the proposals. It's amended its own bill, after the Plaid Cymru MP Ben Lake had proposed a similar amendment. The decision was welcomed by Ynys Môn's representative in the Senedd.

An island’s boundary is not arbitrary, and that’s why Ynys Môn has been a unit at local government and parliamentary level for centuries. To ‘bolt-on’ a part of the mainland to the island just to make up the population would have done a great a disservice to all those represented - on both sides of the bridges.

Rhun ap Iorwerth MS

Of course, it's impossible to ignore the politics of this decision. In Westminster elections, Ynys Môn is a three-way marginal between Plaid Cymru, Labour and the Conservatives, who won the seat in December's General Election. the Bangor area is considered to have more Labour voters than Plaid Cymru ones -and far fewer who support the Conservatives.

Nevertheless, Labour also welcomed the announcement, though arguing that a bigger climb-down was required.

While the Government’s U-turn on this issue is welcome, it simply does not go far enough. The Tories continue to disregard representation in Wales, with Wales set to lose 8 MPs at the next boundary review. The UK Government’s reckless actions will weaken representation for Wales while increasing the number of English seats, risking putting further strain on the integrity of the Union.

Nia Griffith MP, Shadow Welsh Secretary

It's highly unlikely that the government will accept that argument and Wales will end up with fewer, larger seats.