By Andrew Gimson
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Nothing beats the experience of watching Prime Minister's Questions on television. It enables one to see in close-up the faces of the front-benchers sitting next to David Cameron and Ed Miliband, and to tell from their expressions what they think of their leaders' performances.
Harriet Harman resembles an aunt who has come along to watch her nephew take the lead part in the school play, and is saddened to see just how inadequate the lad is turning out to be. As a loyal member of the Labour family, she composes her features into a matronly mask of only faint disapproval, but no one is deceived into imagining she feels the slightest bit enthusiastic about young Miliband.
Nor does Ed Balls betray any trace of admiration for his leader's performance. Balls believes he could play the part with far greater brio and intellectual audacity himself.
But one cannot pretend that Cameron's neighbours look any happier. Nick Clegg has the air of a man who has had the stuffing knocked out of him, while George Osborne appears to be in another world, brooding on sorrows which have no connection with the subject at hand.
Which was health. Miliband was not bad, but as so often one agreed with Harman that he could have been better. The Leader of the Opposition chose a dodgy analogy: "Accident and Emergency is the barometer of the NHS…telling us it is a system in distress."
But that is not what barometers do. They measure atmospheric pressure, and tell you how the weather may be going to change. Miliband would have been better off with a medical instrument which tells one when the patient is at risk of imminent death.
But Miliband did at least manage to provoke a rise in the Prime Minister's blood pressure. Cameron became quite angry, and said if you wanted to see what Labour's record was on health, you had "only got to read the report into the Stafford Hospital".
Miliband considered that in poor taste. It was in poor taste, but since the horrors of Stafford have raised questions about the NHS which remain unanswered, the poor taste was justified.
Cameron also dwelt at some length on Labour's wretched stewardship of the NHS in Wales, and gave the House some stuff about targets met and numbers of staff hired: the tractor-production-figure approach to political debate, more suited to a Stalinist than to a Tory.
But the Prime Minister's main aim, of course, was to demonstrate that he himself is in perfect political health, has never felt fitter and is well able to swipe away the jibes of the Leader of the Opposition.
For much of the time while Cameron was speaking, Andrew Lansley, the Leader of the House, was also in camera shot. It cannot be said that Lansley, who used to be Health Secretary, betrayed any sign of spontaneous admiration for his leader's performance.
Neither Labour nor the Tories knows how the political weather is going to change between now and 2015, and neither party is being offered much in the way of encouragement by its own leader.