What's holding Cameron back?

Watch the Bottler on PMQs and a consistent picture emerges. It is of a man who lacks not just any vestige of charm, one capable only of thudding his fist onto the dispatch box, jaws grinding fit to reduce his teeth to rubble, outrage bursting from every pore, but who cannot, will not, may not ever allow himself to answer any question directly.

The kind of thunderingly dull rumbling that results – of lowest inflation, record employment, lowest interest rates, difficult decisions, long-term prudence, global financial turbulence, compare our record to the Tories, higher spending, never been in better shape, NHS thriving, world class schools, vision for the future, etc, etc, etc., the whole endlessly, numbingly repeated – has been only too well documented.

But what, recently, has become is so striking is just how obviously bogus the factual bases for these claims are. At best, they are deliberate distortions; at worst, active lies.

The saintly Matthew Parris has twice highlighted Brown's outright falsehood that Dinky 'Dave' Cameron was Norman Lamont's 'principal' economic advisor in 1992. Fraser Nelson has similarly precisely skewered the Bottler's claims that inflation is at a near historic low.

But the interesting question is less why the Bottler persists in these transparent half-truths. It is why Cameron doesn't nail him for them.

A key reason for the landslide success of New Labour in 1997 was the relentlessness and ferocity of its attacks on Major's disintegrating government.

Why doesn't Cameron go for the jugular in the same way?

I am not sure I understand.

The Bottler is a sitting target.

Dancing around him with one eye on the BBC's reaction is not enough. Cameron needs to get the Bottler in his sights, take a deep breath, pull the trigger – and keep his finger on it.