The former Chief Secretary to the Treasury, David Laws, has never before released the "no money" letter which was written by his predecessor in the Treasury, Liam Byrne.
Even when David Cameron's former communications chief, Andy Coulson, asked Mr Laws to release it - he refused.
It was written on 6th April 2010 - the day on which Gordon Brown called the election.
Why has David Laws released the politically sensitive letter now?
It is no coincidence that the coalition will, on Wednesday, outline its spending plans for 2015/16.
George Osborne has just agreed the budgets for every government department. He has found the £11.5 billion of cuts he was looking for.
The release of the letter - more than three years after it was written - shows how the both the Conservative and Liberal Democrats want to remind voters about the state of the nation's finances in 2010.
They hope it will help to frame the spending reductions on Wednesday. Inevitably they will lead to some unpopular cuts in many departments.
And after Labour's change of direction (Ed Balls has announced he will stick to the coalition's spending plans if Labour win in 2015) the coalition is having to rethink how it can sell it's own economic plan.