Leading Article: A victory that only exposes Mr Brown's weakness

In winning, however narrowly, yesterday's vote on extending the permitted period of detention without charge, Gordon Brown will believe he has secured for himself a slightly longer lease on his premiership. But the slender margin of the Government's victory and the price Mr Brown was compelled to pay have hardly enhanced his stature. On the contrary, they only exposed his weakness and lack of authority.

The concessions the Prime Minister made – most of them to his own backbenchers – comprised a demeaning rag-bag of promises that made no logical sense at all, except as a means of buying votes. They included ex gratia payments to anyone whose detention beyond 28 days is held to be unjustified and an undertaking to support the lifting of EU sanctions against Cuba.

Like all debts, these could come back to haunt the desperate individual who incurred them. What exacerbates the expense, though, is that they were all for the sake of a knife-edge vote that the Prime Minister could so easily have avoided simply by leaving the anti-terrorism legislation as it was. Mr Brown well knew what political trouble detention without charge had caused Tony Blair. Yet he insisted on revisiting it, despite a steady stream of warnings, not just from civil liberties advocates, but from the Director of Public Prosecutions himself and many others of equivalent authority, that the country would be no safer from terrorist attacks as a result.

It was with a grim irony that, on the same day the Commons voted on this draconian bill, we learnt that a secret government intelligence assessment of al-Qa'ida had been left on a train seat. A more perfect illustration of this administration's ineffective authoritarian tendencies could scarcely be imagined.

Yesterday's proceedings in Parliament offered a truly looking-glass perspective on British politics in the year 2008. There was Mr Brown (Labour), at Prime Minister's Questions, citing in his support the overwhelming popular backing for 42 days' detention, as evinced by contributors to the ConservativeHome website. There was David Cameron (Conservative), responding that it was the duty of political leaders to be above crude populism – or words to that effect.

Anyone who hung around to listen to the actual debate could have been forgiven for concluding that David Davis, leading the Opposition challenge, was in fact a spokesman for the liberal left. Citing the imperative to respect fundamental rights and demolishing the notion that the number of terrorist plots had increased in the past two years, Mr Davis said experience showed that anyone locked up without charge was more likely to be proven innocent than guilty. He was taking issue with a Home Secretary who had just given the most convoluted explanation of why, in her view, habeas corpus had not been subverted, even though its most elementary safeguard – a maximum of 48 hours' detention without charge – had been compromised when the 28-day provision was passed.

Yesterday's battle in the Commons was well-fought by the defenders of civil liberties, on all sides of the House, but in the end it was lost. It is no credit to the way of British politics that, in the very short term, the Government's petty inducements and bullying arm-twisting paid off. This was, though, just the opening engagement. The torch of resistance now passes to the House of Lords, whose doughty defence of Britain's threatened freedoms in recent years has more than justified the continued existence of the second chamber. We trust that – as with previous excesses of anti-terrorist legislation proposed by this government – the Lords and Ladies will show their mettle.