The first prime minister's questions since the passing of Eric Forth began with warm and sincere tributes. And the late Bromley and Chislehurst MP, whose usual seat was left empty by his Conservative colleagues, would have enjoyed the rough and tumble of another uncomfortable session for Tony Blair.

As David Cameron said, Forth was a "master" at the despatch box, something the usually adept Blair has failed to be in recent weeks.

While good PR for himself, John Reid's frank admission that the Immigration and Nationality Directorate is "not fit for purpose" was never likely to help the prime minister in parliament, with the Conservative leader's first, albeit obvious, question being why not when the government has been in power for nine years.

Just to rub it in, he provided a quote from Blair praising the IND as a "transformed part of the Home Office".

The premier fell back on a combination of his three favourite tactics: Blaming the previous (Tory) government, going through his own administration's record and answering a different point about asylum.

With all three now worn threadbare rather than thin, Cameron hit back: "To try to blame previous Conservative home secretaries just won't wash. He'll be blaming Sir Robert Peel next."

It was a good line and put Blair on the back foot for the remainder of their exchange, despite his protestations that he was taking responsibility for the numerous problems afflicting the department.

His failure to answer the question became a theme, as he sought refuge in another favourite approach: attacking the Tories for voting against measures that would have made the situation better.

This was in response to a request to know why Tony McNulty - judged "too incompetent" in Cameron's words to run immigration - had now been put in charge of the police instead.

The wave of sedentary calls for him to address the point became so loud that the Speaker had to intervene and demand that Blair be allowed to do so.

So keen were Tories for him to do exactly that that they replaced their shouts with "shusses", only for Michael Martin to threaten to suspend the sitting if order was not restored. While notionally protecting the prime minister, it was also a snub for Blair in the sense that he could not command the House on his own, further undermining his already fragile authority.

Neither was he helped by his own backbencher Stephen Hepburn, who said on the seemingly innocent subject of asbestos compensation that he did "not expect the prime minister to give a decision or an answer now".

That led to Sir Menzies Campbell who, despite appearing to have inherited former Tory leader Iain Duncan Smith's famous frog in the throat, steadied himself by paying his own tribute to Forth, whose wit had caused one of the Liberal Democrat leader's worst Commons moments when he called on him to declare his interests in a question on pensions.

Sir Menzies was generous enough to acknowledge Forth's regular tormenting of him and, perhaps in his absence, had one of his better days.

He too went on home affairs - something of an open goal in the light of recent events - asking why the promised firearms register had still not been introduced and whether the Home Office was fit for purpose or not (having reminded Blair of an answer three weeks ago that it was). And he just about scored by failing to extract a direct response from the prime minister himself.

Cameron came back for a bit of Brown-bashing and had the rare success of making the chancellor smile by asking why Blair wouldn't let him take over.

Light relief for Labour MPs came from mocking Tory Tim Yeo's posh accent and hearing from their own Dennis Skinner that the Conservatives, as well as the Home Office, had employed illegal immigrants.

But it was Opposition MPs who left with smiles on their faces after Blair openly admitted his strategy for the day in response to a question on reports that he had tried to get John Prescott to give up his grace and favour home.

"I have no intention whatsoever of discussing the reshuffle or any matters associated with it," the prime minister said.

The verdict

Blair: 5/10 - Will be relieved to take refuge in the White House tomorrow after Home Office week from hell.

Cameron: 8/10 - Well judged balance of humour and hard politics.

Campbell: 6/10 - Nerves betrayed by ropey throat but at least got some better questions out of it.