I think enough has probably already been said and written about David Cameron’s latest Flashman moment, though I’m sure Michael Winner was dead chuffed to be trending on twitter alongside the Labour MP to whom the PM directed his ‘calm down dear’ jibe. Have to confess I didn’t realise this was a Winnerism.

It was a moment that revealed something of Cameron’s character under pressure (a theme developing), but before we all get carried away, it was not a moment to change the political landscape.

The real significance of yesterday lies in why he was in that mode. And the answer lies in the fact that once again Ed Miliband got under his skin, first on the economy and second – a real Cameron weak spot – in relation to the NHS. Ed asked a series of straight, fact-laden questions which reminded Cameron of two things he does not like to admit – on the economy, Plan A is not going according to plan; and on the NHS, the government’s reform plans are not thought through, not popular with those who run the NHS or those who use it, and politically toxic, not least because they have no mandate for them.

Though Cameron is unlikely to feel his ‘calm down dear’ moment was a success, in some ways the furore it launched was useful to him. If the nation’s news bulletin watchers last night had seen the exchanges on the NHS, they really would have been worried. It may be this, rather than his non-membership of the Bullingdon, that led Nick Clegg to look so uncomfortable as George Osborne laughed uproariously at Cameron’s ‘humorous’ (the Downing Street line) put-down. It is why Ed should keep coming back to the NHS again and again and again.