The fight facing Brown | Sketch | Red Box blog | The bribes | The concessions | Cameron the winner

A win is a win, however achieved, and with whatever allies. But despite Gordon Brown’s evident relief at his first victory in many months, the Commons vote is far from the end of the story.

The impact has to be measured over varying time spans. In the short term, the Government has won a rare tactical coup over the opposition parties. Tory MPs were furious, some attacking the Democratic Unionists as traitors for using their key nine swing votes to back the 42-day proposal. Rumoured, though denied, deals with the DUP have parallels in the bargaining done with Unionist MPs by previous governments in a precarious position, as the Callaghan administration tried to do unsuccessfully on the eve of its loss of a no-confidence motion in March 1979.

Put another way, if the Government had lost, Mr Brown’s authority would have been undermined further and there would have been another round of media stories, and speculation, about his leadership. The freefall in his political standing would have continued. As it is, he may have stabilised his position among Labour MPs, at least temporarily.

But any celebrations could fade quickly if you look beyond this weekend. There is virtually no chance of the House of Lords approving the Bill to extend precharge detention to 42 days in its present form. The Lords prides itself on defending civil liberties and it has amended several counter-terrorism Bills since 2001.

Labour does not have a majority in the second chamber and can easily be outvoted by Conservative and Liberal Democrat peers combined however the crossbench, unaligned peers vote. But Labour also faces a large rebellion in its own ranks. Lord Falconer of Thoroton, the former Lord Chancellor, and Lord Goldsmith, the former Attorney-General, have said they will oppose 42 days, and will be joined by many other Labour peers, while many normal loyalists may abstain. Of course, there may be cross-voting, with some opposition peers backing the proposals, but the odds are that 42 days will be defeated heavily. Peers will feel freer to act because of the wafer-thin margin in the Commons.

The question then is how far the Lords will press their objections to 42 days. Much depends on the size of the Lords majority rejecting the Commons vote. In the past, controversial proposals on detention powers have bounced between the two Houses in what is known at Westminster as parliamentary ping-pong.

But, usually, and after the introduction of safeguards, the Lords has eventually accepted the will of the Commons. Feelings are running even higher this time, therefore increasing the chances of a long-running confrontation.

In political terms, Mr Brown reckons that he is on the side of public opinion, which has backed 42 days by a very big margin in all polls, despite the criticism of civil libertarians. He has staked a lot on playing the national security card and has depicted David Cameron as pursuing “opposition for opposition’s sake”, and being implictly “weak” on terrorism.

The fate of 42 days, and the long-term political fallout, will depend not just on what happens in Westminster over the next few months but also on whether there are further terrorist outrages.

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