To Conservatives, securing boundary reform is one of those happy causes which is both morally just and practically necessary.

It is just because it is scarcely defensible for Labour seats to be systemically smaller and thus more efficient than their Tory-leaning counterparts.

It is essential because the majority is miniscule, and if the Party slips up the Opposition might just manage to stagger over the line – with help from the SNP, Plaid Cymru, et al – and, in their despair, enact proportional representation.

Yet boundary reform, coupled as it is with a cut in the number of MPs from 650 to 600, entails a significant problem: it risks leaving some sitting Conservative MPs without seats.

No matter how demonstrably just and vital to Conservative interests boundary reform happens to be, any MP who stands to lose their seat will almost certainly, after careful consideration, find it to be the wrong course – as will many of their friends.

So it has proved: following threats of a major rebellion against the plan, David Cameron has made a ‘No Tory Left Behind’ pledge to ensure that every Tory MP who wants one has a seat to fight at the next election.

Such a promise is a sign both of just how seriously the leadership is taking the task of securing fairer boundaries – the importance of which we highlighted in our Securing the Majority series in May – and of how vulnerable the Government’s small majority makes it to internal pressure.

Yet it has troubling implications for the candidate selection process.

At the minute, the final call on the selection of candidates rests with local associations. CCHQ acts as gatekeeper to the candidates list, and members of that list then interview with associations.

There are a lot of people on the candidates list, and there is little reason to think that competition over an entirely new lot of seats ahead of 2020 is going to be anything less than intense.

How, then, will the leadership be able to ensure that all sitting MPs get reselected?

One can see ways that might go some way to solving the problem, such as treating MPs whose old seat forms a certain percentage of a new seat as ‘sitting’ for that seat.

But there will still be some number of sitting MPs who need to be reselected for a new constituency.

At that point (assuming that associations don’t freely choose them all over all the alternatives on offer) CCHQ seems certain either to have to force them on associations or break its promise to those MPs.

The leadership’s last attempt to impose preferences on local parties in such a manner passed into infamy as the A-List, an experience they should be keen not to repeat.

It alienates associations, disenfranchises party members, and will greatly irritate talented and enthusiastic would-be candidates who aren’t given an opportunity to compete.

Such high-handed treatment is not likely to reverse the ongoing decline in membership, which we at ConHome think is essential to the long-term health of the Party.

Nor should we ignore what is lost if ensuring the reselection of all sitting MPs means “that it will be almost impossible for Conservatives hoping to become new MPs at the next election to find a seat”, even if we conclude that fairer boundaries is a greater prize than a hypothetical ‘Class of 2020’.

The leadership has set itself a tricky challenge: to pursue crucial reforms and whilst at once assuaging the concerns of MPs, defending the remaining rights of the membership, and advancing the long-term interests of the Party.

With the EU referendum already promising to strain the Tory coalition’s internal bonds in the years ahead, it is essential that they rise to it.