The Liberal Democrats, their leader told us yesterday, are going to treat the voters as grown-ups.
"All our figures," said the man in charge of their manifesto, "add up to the nearest penny".
Er, up to a point. I type hotfoot from a Lib Dem news conference at which the man who wants to be Secretary of State for Wales after the general election admitted he doesn't know what his party's policies mean for Welsh pounds, let alone pennies.
Roger Williams told us: "The politics of plenty have gone. We have got to be responsible."
So what, I wondered, would be the financial consequences of the Lib Dems' decision to scrap or delay several of their cherished policies in England?
"We are going to have to work that through, we haven't worked that out yet."
Would a Lib Dem government go ahead with the defence training academy at St Athan or scrap it, as suggested by deputy leader Vince Cable?
Roger Williams: "It isn't clear from what the Government has said whether the St Athan money is new money or money used for training. If it is new money, that is challenging."
Would a Lib Dem government go ahead with the electrification of the rail line between London and Swansea?
"We haven't got any plans to either postpone it or reject it."
Things will become clearer, possibly, later this week when Mr Williams meets Danny Alexander to discuss "Barnett consequentials" and other spending issues.