Firstly, Cameron didn't say it was necessary. He merely used that example to illustrate what he was saying.
Cameron's first act as PM was to repeal Labour's ID Cards Act (which was compulsory fingerprinting, numbering and recording on a national database to hook up all govt databases) and destroy the hard disks Guardian-style. Maybe this is where he got the idea.
He also attended the inception meeting of NO2ID, the immensely successful campaign that Labour's Home Minister Secretary at the time, David Blunkett, acknowledged in his final speech.
The Tory Snooper's Charter was a mess. Expert after expert (including industry data-rape experts from Google et al) slagged it off in official proceedings and even an open letter. We're kinda used to Govts being clueless about IT but what was properly disturbing was how the Home Office ignored all this clear and helpful feedback. So certainly, Theresa May should be sacked.
I'm not sure Cameron ever stepped in until now. Under pressure from his party, Clegg eventually said he wasn't going to support any such Bill and so that killed it for this Parliament.
We badly need an Act clawing back some of the surveillance powers of the state. They can do already do any surveillance at the ISP level they want as well as lock up people for not disclosing their public keys. There are no checks on that power whatsover in this country bar possibly The Guardian.
So that's a summary of where we are. The debate I wanted to highlight is how do we assess Cameron's views on this:
Few people know this but Cameron used to write a column for the left-wing Guardian. And he was far more liberal a couple of years before he got into power.
Has he gone from liberal to totalitarian in 3-6 years? If so, why? Is it merely scary-sounding intelligence reports or is it possible that our secret services are blackmailing him?
Or is he merely trying to shift the cost burden of surveillance from the state to the ISP/customer? And if so, why is he talking about a dead Bill which he has almost no chance of reintroducing (since he'll almost certainly be kicked out in 2015)?