Johnson’s boundary review is likely to benefit the Tories at the next general election

And the commission recommendations will be implemented automatically, with no vote in parliament, writes John Rentoul

The PM has been astute enough to bypass a potential rebellion by the Lib Dems (EPA)

Boris Johnson made a decision last week that could make all the difference to the result of the next election, even though that is likely to be four years away. The prime minister signed off on the remit for the boundary commissions that will redraw the map of parliamentary constituencies.

It was announced in a written statement from Chloe Smith, a cabinet office minister. The previous work of the boundary commissions, reducing the number of seats in the House of Commons from 650 to 600 to fulfil David Cameron’s pledge to “cut the cost of politics”, has been junked.

Instead, the commissions will be expected to keep 650 seats, but update their boundaries so that the number of voters in each constituency is as equal as possible. The boundaries were last drawn in 2005-08, so they are now out of date. North West Cambridgeshire has 92,000 registered voters, for example, while Wirral West has just 55,000.