Earlier this week the Government announced that it intends to scrap the current legal requirement for the upcoming boundary review to cut the number of seats in the House of Commons from 650 to 600.

This might seem a slightly odd time to be attending to such issues, but the written statement was apparently made in order to clarify the Government’s position ahead of a debate this Friday on a Private Members Bill. The official justification is as follows:

“Since that policy was established in the Coalition Agreement, the United Kingdom has now left the European Union. The UK Parliament will have a greater workload now we are taking back control and regaining our political and economic independence. It is therefore sensible for the number of parliamentary constituencies to remain at 650.”

However, it is also true that having already faced numerous mutinies on the issue, it was always very likely that this concession would be needed before the boundary review could get through the Commons.

Apparently this is especially true because of the large number of newly-elected MPs sitting on the Conservative benches after the election. According to one analysis put to us, first-term incumbents enjoy a ‘bonus’ when they come up for re-election worth on average around 3,000 votes. This gets disrupted and diminished when boundaries shift.

Slashing the size of the Commons would have led to so much churn as to almost wipe this advantage out across a swathe of the Tories’ new defensive battlegrounds, and been hard to get past the MPs now representing those seats.

Beyond that, we won’t know exactly what this will mean for the shape of the battlefield for the next election until the Boundary Commission produces a new set of proposals. This analysis by Electoral Calculus suggested the Tories would have won a relatively stronger result on the proposed 600-seat map, and it follows that a decision to stick at 650 will likely save more Labour seats than Conservative ones, Furthermore, if the Tories are winning in new parts of the country the partisan advantage of equalising constituency sizes may well be less than it might have been in 2010 or 2015.

But regardless of the outcome for individual parties, it is undoubtedly true that the current constituency boundaries are out of date, as are the assumptions baked into the upcoming review by the Coalition.