17:25

There used to be a time when politicians just made promises, and expected people to believe them. Then, as public scepticism grew, Tony Blair developed a new strategy to persuade people he was sincere; he wrote his commitments out by hand. (He did this during the referendum on the Good Friday agreement, and with part of Labour’s 1997 manifesto too, I recall, and other politicians have tried the same trick, most recently in the Scottish independence referendum.) Later Labour developed another ploy; passing legislation committing it to doing something it said it would do anyway (eg, reducing child poverty.)

Now Ed Miliband has gone one step further: not content with affirming promises by hand, or by statute, he has hired a stonemason to carve them into a block of granite (or whatever it is).

At this stage of the election campaign we all need a bit of a laugh, and #EdStone has certainly provided some welcome entertainment. And some of the mockery is undoubtedly deserved. Announcing that this slab is heading for the Downing Street garden was probably a mistake, and, as John Rentoul argues, it would be easier to admire the pledges stone if some of the promises weren’t so vague.

Still, to his credit, Miliband is trying something imaginative to tackle the problem of trust.

Is this Labour’s “Sheffield rally moment”, as George Osborne suggests? (See 12.45pm.) Almost certainly not. (The psephologists argue that even the Sheffield rally wasn’t really a Sheffield rally moment.) David Cameron argued that the move cast doubt on Ed Miliband’s judgement but, if it was silly, it was certainly no sillier than last week’s tax lock law proposal from the Tories.

Here are the key developments from today.

Cameron has said that Miliband’s decision to commission a pledges “tombstone” for the Number 10 garden casts doubt on his judgment.

Cameron has urged potential Ukip or Lib Dem supporters who want him as prime minister to vote Conservative. In a speech he said:



If you have got a view on who you would prefer as your prime minister express it at the ballot box. The outcome will not be decided any other way. Do not risk voting for another party and hoping that is the outcome. If you want your preferred prime minister get out there and vote for it.

Labour has highlighted the Tories and Lib Dems’ refusal to rule out raising tuition fees, and repeated its pledge to cut them to £6,000. The SNP has also said it would vote with Labour on this. (See 4.17pm.)



Labour BIS Team (@LabourBIS) Nick Clegg broke his promise and trebled student fees - don't let him do it again pic.twitter.com/AMv3DYoalZ

That’s all from me.

Thanks for the comments.