Image caption Standing room only at a recent Prime Minister's Questions

Who would vote to sack themselves? While David Cameron has just decided it's not really worth being a backbencher, the Boundary Review will in contrast set off frenzied scraps and dealings between MPs to determine who gets to hold on.

Labour MPs are likely to take the biggest hit, from the first draft of the new political maps for England and Wales released today. But one educated Westminster guess suggests that 17 Tory MPs might be out of luck too, with 23 Labour seats going, and three Lib Dems.

Don't forget, MPs have to agree these proposals - some of them will be asked to vote to sack themselves.

Before the referendum there was a lot of scepticism in Parliament about whether the review would actually happen. One minister, still in government now, told me "we'll never get it through".

Other Tory MPs said that the changes would simply never happen, and predicted that David Cameron would ditch the review as a gift to grumpy Eurosceptic MPs if he had won the referendum.

No 10 denied that, insisting the changes would be his "legacy to the Tory party", and that the review would essentially make the system fairer and conveniently for them, make Conservative victories easier to achieve.

But Theresa May is perfectly prepared to ditch the previous PM's promises, still has a tiny majority and a difficult agenda to pursue.

With risks of huge discontent over Brexit and grammars already, it would be one way of mollifying angry backbenchers as and when things get tough.

It's worth watching today and in the coming weeks to see whether this is another of David Cameron's promises that will bite the dust.