Bipartisanship sounds fine in theory but it can often be unworkable and even damaging in practice. At times of financial turmoil and uncertainty, the public expects politicians to put party differences aside and to act in the national interest.

Hence, the competition among the three party leaders to appear statesmanlike and serious in tone. They want to be seen rising to the gravity of events and showing that they understand how the world has changed. In that respect, David Cameron got it right yesterday. He was in tune with the public mood and made some positive suggestions about the legislation. That is certainly preferable to the partisan squabbling in the US House of Representatives.

In the paradoxical manner of bipartisanship, Mr Cameron also gained an advantage in party terms. He appeared prime ministerial. It was a skilful performance very much in the Tony Blair style. Of course, there is always an element of self-righteousness, empty good intentions and opportunism in such appeals; remember it was only two days earlier that Mr Cameron launched his strong “from boom to bust” attack on Gordon Brown.

But Mr Cameron’s approach presents a challenge to Mr Brown. He is working around the clock to handle the financial storm, with his commitment “to take whatever action is necessary”. He has the advantages of experience and authority, as some recent polls have shown. But he finds it hard to get the political tone instinctively right in the Blair/Cameron way.

On the substance, the parties may need to cooperate, both to secure rapid passage of legislation and to marshal “public support behind some big decisions”, as Mr Cameron said yesterday – before George Osborne’s rapid visit to London to see Alistair Darling. But there are big differences between the British and US situations. Unlike in America, legislation passed this year has already been used here to nationalise troubled banks, though there are not yet new powers for the Bank of England to rescue and reconstruct them. Moreover, Mr Brown has a secure Commons majority and does not need the votes of Conservative MPs.

Bipartisanship is not some panacea. There can be honest differences over the meaning of the national interest. And however much voters say they dislike adversarial politics, the time to get worried is when there is a cross-party consensus. This has often meant that poorly thought-out ideas are not properly questioned. Remember the consequences of the consensus, and absence of scrutiny, on the child support and dangerous dogs legislation in the past.

Legislation should certainly be a priority when Parliament returns on Monday, but the detailed provisions should not just be nodded through. There are real questions about who should bear the risk and costs, let alone longer-term issues of regulation.

There is a big difference between agreeing on the urgency of sorting out a problem and not undertaking the necessary scrutiny. As Mr Cameron said, there “should never be a blank cheque. We should not suspend our critical faculties.”

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