GORDON BROWN has walked on water during his first week in No 10 but found himself sinking in his first head-to-head with David Cameron yesterday.

The new Prime Minister stumbled and stammered his way through an uncomfort able first 30 minutes of combat, his nerves clearly on display.

One could sense the lurking suspicion that Mr Brown lacks the verbal dexterity to triumph in the Commons chamber spreading along the Labour benches like a virus.

Worst of all, Mr Cameron, constrained by the sombre mood brought on by the fresh terror threat, played softball yesterday.

What happens when he moves in for the kill?

It is hard to pinpoint where Mr Brown most went wrong as he was forced, time after time, to fall back on appeals for "bipartisanship". That can’t last, once normal party politics resumes.

Was it the several occasions when the Prime Minister played for time by stuttering ‘Mr, Mr, Mr, Mr, Mr, Mr Speaker......’ before finally giving his response?

Was it when, struggling to explain why the Government has failed to follow through on its pledge to ban the extremist group Hizb ut Tahrir, he begged: "I have only been in the job for five days!"

That was feeble, even ignoring the fact that it was a full seven days since the No 10 door opened for him.

Or was it when Mr Brown’s old enemy John Reid, now on the backbenches, had to ride to his rescue, by pointing out a ban on Hizb ut Tahrir had twice been rejected for lack of evidence?

Perhaps it was when Liberal Democrat leader Sir Menzies Campbell floored him by pointing out, to laughter, that Mr Brown’s "open door" was "more like a trapdoor"?

It wasn’t a car crash - just a nasty skid on a tricky bend - and, of course, the prime minister will surely improve when he gets a few sessions under his belt.

Furthermore, a return to partisan battle in the weeks ahead may favour Mr Brown, allowing him to unleash that famous clunking fist.

But one serious disadvantage is that, unlike his quick-witted predecessor, he cannot flick though a bulky dossier for answers - his poor eyesight rules that out.

Does it matter? Probably not, if Mr Brown continues to perform skilfully outside the chamber and convinces the public he is a welcome fresh face.

Nothing saps party morale more than a failure to cut the mustard at Prime Minister’s Questions. Mr Brown must improve.