David Cameron’s tone was much improved. We saw some of the gleams of humour which alone can make such a lengthy election campaign tolerable. After listing various subjects on which he observed that Ed Miliband has “absolutely nothing to say”, the Prime Minister concluded with the words “this year it’s a Silent Night”.

One would not wish to pretend this was worthy of Oscar Wilde. But the pleasure the Prime Minister took in the line – for he has never been a man to refrain from laughing at his own jokes – helped to carry the thing off. Cameron continues to be very rude about the Leader of the Opposition  – “he’s a waste of space” – but today sounded less brutal and more charitable.

This could just be a pre-Christmas lull. But it could also be a sign of growing prime ministerial confidence. The Conservatives have a good story to tell on the economy. Labour appears not to have much of a story at all.

Miliband did what he could with the accusation that the Tories want to take us back to the 1930s. This was based on a forecast from the Office for Budget Responsibility that public spending will fall, on Conservative plans, to 35.2 per cent of GDP in 2019-20, the lowest level for 80 years.

Perhaps, one might think, we are at last getting over the appalling economic consequences of the Second World War. But of course, to suggest that spending in real terms will be anything like 1930s levels would be absurd. In real terms, as Cameron pointed out, Conservative plans would only take us back to 2002-03, when the country had for several years been governed by Labour.

So Miliband found it hard to frighten people into believing that “the mask slipped in the Autumn Statement” and the Tories really do want to return to the 1930s (when Neville Chamberlain was actually running domestic policy rather well). And Cameron found it easy, with support from his own benches, to allude at frequent intervals to the continued fall in the unemployment figures.

But the Prime Minister’s happiest stroke came when he quoted from a Labour briefing document which states, on page 16, that on managing the economy “the Conservatives have a 17 per cent lead”. Even Theresa May’s face lit up at this news. The Conservatives really do believe that here they have a decisive advantage.

Douglas Carswell (UKIP, Clacton) by an odd slip of the tongue referred to the Prime Minister as “my honourable friend”. Can it be that he already wishes, in his heart of hearts, to return to the Conservative Party? If so, the friendliest and most festive welcome should be extended to this prodigal backbencher, with the fatted calf killed in his honour, and a general willingness to forgive his recent rush of blood to the head.