Now the general election has been called, the NHS can finally start crossing off the days until some honesty returns to the debate about the future of healthcare.

The public has no chance of understanding the likely impact of the spending squeeze when the two main parties appear to be using the Magic Circle as their economic think tank. The government was rightly pilloried in Parliament for claiming its bill extending free social care would be funded by local government “efficiency savings”, when ministers know councils face severe and prolonged spending cuts far worse than those the NHS will suffer.

While the public might be fooled, only a particularly credulous manager would be taken in by promises to protect services or increase spending

Similarly, the Conservatives’ claim that they would fund £200m of additional cancer drugs by not implementing Labour’s national insurance increase in full does not withstand a moment’s scrutiny.

Politicians trading blows with such flimsy weapons does little to reassure health service leaders and staff that the tough post-election decisions will be based on rigorous analysis.

While the public might be fooled, only a particularly credulous manager would be taken in by the promises to protect frontline services or increase real terms spending. To make these electoral one-liners a reality the cuts to services such as social care or defence would have to be so extreme that no government could countenance them. Hospitals and primary care trusts are bracing themselves for cuts. Big ones.

But where? Immense damage could be inflicted on the NHS if the next government fails to take decisions on sound evidence. Under Labour there has been so much cash sloshing around NHS corridors that the effects of poor policies and unintended consequences have often been ameliorated by the sheer volume of resource coming on stream. In the new age of austerity, policy makers and managers will not have that luxury. If politicians do something dumb we won’t have to wait for the National Audit Office inquiry to know how much harm has resulted.

This week the cooperation and competition panel sets an example of how to keep politicians and managers focused on facts and data. It is finalising a report to be published after the election into the link between clinical outcomes and patient numbers. The panel warns that foundation trusts looking to take over weaker trusts cannot simply claim bigger is better; they must argue the specifics for a particular service. Give them the evidence.

Evidence for policy decisions will always be conflicting, of course. Clinicians are not far behind economists when it comes to providing contradictory interpretations of the same data. Overlay this with the vested interests - and genuine concerns - of staff facing the shutting of a facility, and the difficulty of discerning the right way forward is all too evident.

But this is at least the correct starting point. Shadow health secretary Andrew Lansley should no more be allowed to get away with asserting that GP commissioning is going to improve quality and productivity than incumbent Andy Burnham should be allowed to marginalise the private and voluntary sectors without sound reasoning.

The King’s Fund was right to shoot down the Tories’ bid for the “I’m afraid of getting cancer” vote last weekend. Bringing sanity and clarity to the health policy debate will be hard, but those in influential positions must stop politicians feeding public ignorance about the NHS.

Managers, think tanks, regulators, the NHS Confederation, the royal colleges and the likes of Dr Foster should not waste much time trying to ingratiate themselves with the new ministers. Once the obligatory letters of congratulations have been posted they should firmly, relentlessly force the new government to ground its policies in reality, not base them on anecdote, prejudice and whim.

Flimsy electoral one-liners must make way for realistic policies