SINCE MPs last met for Prime Minister's Questions, much has happened in the world.

Along with cabinet reshuffles, international wars and the defection of Tory backbencher Douglas Carswell to Ukip, the independence referendum campaign has, of course, entered its final phase.

Over the summer the SNP has made much play of its claims that only independence can protect the NHS from what has happened to the health service in England.

Who should be the first MP to pop up to ask a question about Scotland?

Only the architect of those said health reforms, Andrew Lansley.

You could almost hear the cheering from the Yes campaign.

Nevertheless, Mr Cameron took the theme and decided to run with it.

"Lies" he shouted at the SNP.

"Keep talking Scotland down," Angus Robertson, the SNP MP, shouted back.

"Give us more lectures," added his party colleague Pete Wishart.

He was not to be disappointed from the Prime Minister.

That inspired such chuntering from SNP MP Angus MacNeil that the Speaker John Bercow thought he had a good line. "You aspire to be a statesman," he told him. "Try acting like it."

All this is not to pretend there was no intervening on private grief over the Tories' problems with Ukip.

A Labour MP pointed out that the day of the by-election triggered by Mr Carswell will be the Prime Minister's 48th birthday.

Mr Cameron remained resolutely upbeat. Well, as much as he could be under the circumstances.

He pleaded: "I am sure I will be getting all sorts of pleasant surprises on my birthday.

"Please do not spoil it by letting me know what they are."