What would Tony do?

It is easy to tell when David Cameron is wading into trouble during interviews. He becomes defensive, audibly irritated and — as an emergency self-calming measure — tries to force a little laugh. He performed this telltale routine on the radio on Monday, when challenged over his NHS reforms. He had promised the country no more upheavals to the NHS — and had clearly reneged. How to get out of this tight spot? Cite Tony Blair. In a speech later that day Cameron invoked the former PM’s name to justify himself. Bringing in these health reforms was just what Blair would have done. How could any sensible person disagree with that?

It might sound like an odd line of argument to the many people who regard Blair as a charlatan. When word came that he would give evidence (again) to the Iraq inquiry on Friday, there was much excitement in the Cameron circle, where he remains something of a political hero.