I asked David Cameron at Prime Minister's questions on Wednesday a question showing that George Osborne's boasted "recovery" was no such thing.

"Is the PM aware that, according to the Economist, Britain is now 159th lowest in the world in terms of business investment, just behind Mali, Paraguay and Guatemala?

"Could he therefore tell the House when, under his esteemed leadership and that of the Chancellor, Britain might now expect to catch up with Mali?"

Cameron's reply descended to a depth I don't recall ever witnessing at PMQs over the last 40 years, referring to me as sounding like someone on mind-altering substances like the Rev Paul Flowers.

When I protested on a point of order that this was an unjustified, rude and offensive way to refer to another parliamentarian he pretended it was just banter but very ungraciously withdrew his remark.

The real point in all this is that the nation expects a Prime Minister to behave with the dignity and propriety of his office and not get drawn into saloon-bar insults.

Cameron at PMQs is falling further and further below this standard and sounds increasingly like a fairground bruiser rather than a Prime Minister.

Partly because of Cameron's style - at times patronising, arrogant, insolent and dismissive - PMQs in no longer fit for purpose.

It brings Parliament into disrepute by its noisy rowdiness, its gladiatorial atmosphere turns the public off and the only people who gain are the parliamentary sketch-writers whose relentless iconoclasm and trivialised obsession with personalities drag down politics to inconsequence and farce.

So what should be done to try to restore PMQs to its proper role as a forum for serious discussion of the country's key issues? I think there are four reforms which should produce a big improvement.

There is a strong argument for reverting to the system of closed questions, ie a specific question is asked and recorded on the order paper as in the case of all other departmental questions. This always existed before Margaret Thatcher changed it to open questions where an MP can ask any question on anything.

This latter system, which no individual and not even a versatile Prime Minister can handle with precision, leads to woolly answers filled out with party abuse. Closed questions would concentrate minds much more on serious scrutiny of an issue.

Second, we should also restore the pre-Blair pattern of two 15-minute PMQ sessions per week rather than a single session of 30 minutes. Blair changed it to the latter practice because he didn't want to have to attend Parliament more than once a week. But that has the drawback that it raises the temperature and the noise much more than if there were two shorter sessions.

Third, over the recent period the cacophony at PMQs has become deafening - worse in the chamber than on TV where directed microphones pick out the voice more clearly.

The Speaker tries repeatedly to control the noise volume. He should give notice that he will in future name MPs who are excessively noisy and then when he does it should mean expulsion from the House for a week - or more.

And fourth, if noise levels repeatedly exceed acceptable standards, he should be prepared in extreme circumstances to suspend a sitting for half an hour or more until the House quietens down. He should not have to exercise these measures more than a few times to raise PMQs from its present appearance sometimes as a cross between the football terraces and a nazi rally.

Michael Meacher is Labour MP for Oldham West and Royton