Donald Macintyre's Sketch: Making mountains out of potholes – that’s an idea!

Potholes do roughly for David Cameron what motorway cones once did for John Major. Removing them is an impossible task to complete, or even do that much about, in the lifetime of a government or three. But talking about removing them appeals directly to the Tory (and these days Ukip-leaning) motorist base.

Today a hyper-loyal question from Tory Michael Ellis took this to a new ideological level. He said it was thanks to the government’s “long-term economic plan”, that the £3.3m Northamptonshire had been given for “fighting potholes” can show how (double highway metaphor alert) “only the Conservatives have a plan that puts Britain on the road to recovery, whereas the Labour party would drive the country’s economy off a cliff.”

David Cameron rose to the occasion, helpfully explaining that this would be enough to fill in “a staggering 62,000 potholes” which “damage people’s cars, motorbikes and cycles when they are on their way to work, and mending them is good for hardworking families.” (It’s also good for teenage joyriders and single layabouts with wheels, but he didn’t mention that.)

He may have had the figure to hand because by this time he was statistics-crazed, having gone a full six noisy rounds on the NHS with Ed Miliband. You could tell that the Labour leader was on somewhat surer ground by the speed with which Cameron reached for the routine lifebelt of Wales – where the Labour administration has its own health problems – and the obviousness with which he didn’t exactly answer the questions Miliband asked him.

But a problem with these titanic statistical clashes – even on a subject as important as the NHS – is that they end up as baffling orgies of category confusion. Miliband: “The NHS has missed the target on access to cancer treatment for the first time ever.” Cameron: “The number of people being treated for cancer is up 15 per cent.” Cameron: “[Under Labour] the average waiting time [in A&E] was 77 minutes; under this Government, it is 30 minutes.” Miliband: “before his re-organisation, the number of people waiting more than four hours was 353,000… That has risen to 939,000!”

And so on. Maybe potholes will be next: “Has the PM read the estimate by the respected Asphalt Industry Alliance that at current maintenance levels, the average frequency for a road to be resurfaced in England is once every 54 years?”

“We have ring-fenced £200m to fill in potholes, which Labour never did.” “But the AA say that highways budget cuts mean £38m per local authority is now needed to do the job.”And Cameron (who always gets the last word) would say: “There are 1,000 more full-time pothole fillers than there were when his party was in office. I’ll tell you what is happening. Labour digs the holes and the Conservatives fill them in!”

Massive cheers from Tory benches. And none of us would be any wiser.