In politics context is everything, even when it comes to sex jokes. But we will get to that.

Before the Prime Minister kicked off his conference speech activists were shown a video of the Tory election campaign.

The same video they had watched numerous times since arriving in Manchester at the weekend (it has been a good way to fill time – and signal a tea break).

But now it was like they were watching it – and its really quite well-known events – for the first time.

They chortled in the aisles at footage of the ‘Edstone’.

They gasped as Vince Cable ("Vince Cable!") lost his seat.

There was a big cheers as Ed Balls lost his and boos when Ed Miliband said during a TV debate that Labour did not spend too much when it was in power.

‘Can you believe that all happened?’, was the apparently prevailing mood.

Some would feel the same after a certain part of Mr Cameron’s speech too.

For the main part the Prime Minister's words were a confident appeal to the centre ground of British politics.

But he did also address, albeit obliquely, the controversial story about his time at university that so dominated the newspapers in the run up to the conference.

And make a sex joke.

Although, to be fair, it was not immediately obvious that’s where he was going when he mentioned Jeremy Corbyn.

The new Labour leader’s “economics guru” Richard Murphy had a book published, he told the Tory party faithful (thankfully, for the purposes of this story, rather younger this year than in times gone by).

“His book is actually called “The Joy of Tax”,” Mr Cameron said.

“I took it home to show Samantha.

“It’s got 64 positions – and none of them work."

Parts of the hall certainly loved it.

Was Lord Ashcroft watching?

Mr Cameron will have been hoping so.