The 42-day detention row is only the first and most straightforward of the political challenges facing Gordon Brown as he tries to rebuild his authority. More serious, and trickier, are other disputes over fuel taxes, vehicle excise duty, tax cuts and spending increases. They would all cost money that Mr Brown, or rather the Treasury, does not have.

The detention row raises fundamental questions, of the kind we have seen many times since 2001, about the balance between security and civil liberties. The political stakes are high for Mr Brown, but not fatal, as Labour whips try to rally MPs before the key votes this month, but the financial costs are negligible, and the issue is a low priority for many voters.

As senior ministers and government backbenchers agree, disillusioned and former Labour voters are more concerned about rising fuel and food prices, and broader economic uncertainties. There are no easy solutions. The Treasury spent, or rather borrowed, £2.7 billion it doesn’t really have three weeks ago to cut taxes, which it will have to refinance this year. It is no good pointing to the increased fuel and driving tax receipts produced by higher oil prices, since the Treasury is suffering a big cut in revenue from other taxes because of the fall in housing and stock market activity.

The real problem is not fuel duty – 20 per cent higher in real terms in 2000 than now – but rising oil prices. Moreover, any big reversal of policy on road taxes would undermine the Labour Party’s green credentials. Nonetheless, we can expect the cancellation of the planned 2p-a-litre rise in fuel duty and, probably, modifications to the restructuring of vehicle excise duty to hit high-emission cars, including some popular family models.

There is no additional money available for such help, but also any impression that the Government was performing another U-turn and buckling to the pressure of vocal interest groups would undermine Mr Brown’s authority rather than gain him support from voters grateful for the concessions.

These constraints apply even more to the suggestions that Mr Brown has been receiving either to raise public spending or to cut taxes. As several Labour MPs have argued, there has been a shift in the public mood against higher taxes at a time when real incomes are being squeezed, but there is almost no short-term, that is preelection, scope to cut taxes overall.

The daftest advice has been to assume that Labour is going to lose the next election, abandon caution and go for a full-blooded socialist alternative. That is mad, both as a policy and as an electoral strategy. The outcome of the next election is still open, if not wide open. There is a huge difference between a narrow defeat and a rout and those naively suggesting that Labour would benefit from a period in opposition have short memories and did not experience the lengthy agonies of Labour in the 1980s or the Tories after 1997. No sane politician believes that opposition is good for their party.

Mr Brown’s only chance is to try, if he can, to restore a reputation for competence in government. That means sticking to his instincts rather than trying to appease rebels and protesters.

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