It is now three weeks since Ed Miliband launched his unbelievably cunning strategy for prime minister’s questions of asking the prime minister questions.  Mr Cameron, who took up to eight months to work out that his health secretary’s health reforms were political suicide on stilts, cannot claim a reputation for being quick on the uptake. There was, from today’s evidence, no sign that he has yet spotted the Miliband secret weapon, still less worked out how to counter it.

Mr Cameron has available to him the conventional three options for dealing with challenges put to him across the despatch box: he can answer the question; or ignore it; or answer another question altogether. The prime minister is in fact quite good at answering the question when the inclination takes him. When the Conservative backbencher Graham Evans today inquired whether the PM felt that the men of Bomber Command killed in the war deserve to be remembered, he had no hesitation in thinking that to be the case.  Labour members quite often seek to test Mr Cameron’s opinion on whether he is an insufferable Etonian bully-boy, presiding over a Cabinet of monsters steeped in the blood of pensioners, and he rarely feels the need to smudge his reply. Yet when Mr Miliband rises to speak, the prime minister’s certainties desert him.

Both dodging tactics were on display today. There was a period in the middle of the Miliband innings when the prime minister started to answer not the leader of the opposition’s immediate question, but the one he had put to him on the previous go. For a while it looked as if PMQs was going to go the way of the famous Two Ronnies’  Mastermind sketch. If Mr Miliband had had the wit to ask Mr Cameron if he knew what Burke’s peerage was, the PM would surely have replied a study of old fossils.

Perhaps mindful of where this was heading, the prime minister switched tactic. He stopped answering the question altogether. On and on droned Mr Miliband with ever more detailed interrogations about the impact of the NHS reforms. Did the prime minister know how many new statutory bodies would be created by the changes? Well, of course, he didn’t. Nobody does. Mr Miliband supplied an answer – he likes to do that – 521 as it happens, but this has no more status than a child’s church fete estimate of he number of sweets in a jar.  By the time anyone in the Department of Health has finished counting, half of them will have been abolished and twice as many again re-created under different initials. Such is the endearing and enduring nature of British health policy.

The only thing Mr Cameron has to count is the number of the opposition leader’s questions, so that by the time he has had his six, the PM is then free to launch into his pre-prepared rant.  This took the form of a litany of all the things that Mr Miliband hadn’t asked him about – strikes, the economy, Greece and so forth – each of which, according to the prime minister, revealed either political vulnerability or shocking lack of judgement, or both.  It is not the first time Cameron has tried this out and each time I cannot help but imagine him as a suspect under police interrogation. “Ha”, he says, “I notice that all the detective chief inspector wants to know is where I’ve hidden the body; he simply wouldn’t dare to tackle me on my views of 17th century chamber music”.

On the subject of the health reforms themselves, the prime minister was pleased to observe that they had gained the support of Tony Blair and of the former Labour health minister Lord Darzi. However, he mispronounced the latter’s name so it came out as Lord Darz-eye, as if Mr Cameron might have been temporarily under the impression that GP commissioning had been well-reviewed by the prime minister of Afghanistan. Later, a sycophantic Tory MP from Wales, Guto Bebb, observed that Nye Bevan would be spinning in his grave at what Labour was doing to the NHS in the Prinicipality. Regular observers of health politics will know that Nye Bevan has been spinning in his grave for one reason or another ever since he died 51 years ago, and possibly even before that. Another questioner wanted to know about renewable energy to which the answer surely is to harness the power emanating from the founder of the NHS expressing his posthumous displeasure at that organisation’s subsequent and inexorable decline.