MICHAEL SETTLE and TORCUIL CRICHTON

Gordon Brown's slender victory on 42 days' detention without charge was branded "hollow" by his opponents last night after he had to rely on the votes of nine Democratic Unionists and four other opposition MPs, including Tory back bencher Ann Widdecombe and UKIP's Bob Spink.

The Prime Minister's in-built majority of 66 disappeared as 36 Labour MPs - including Katy Clark, representing North Ayrshire and Arran - rebelled on the UK Government's flagship Counter Terrorism Bill. The vote was 315 votes to 306 - a majority of nine.

Had the DUP abstained, Mr Brown's majority would have disappeared, leaving the Speaker, Michael Martin, to use his casting vote. Given that, by convention, he votes with the status quo, then the UK Government would have been defeated.

After the vote was read out, there were heated scenes in the Commons chamber as Tory and Liberal Democrat MPs pointed towards the DUP, accusing them of being "bought".

Outside, Nigel Dodds, the MP for Belfast North who is Finance Minister in the Stormont Assembly, strenuously denied securing a deal with Mr Brown. "There is no question of any deal being done. The decision was made in the best interests of the country on the grounds of national security," he insisted.

Last night it was clear the parliamentary battle is far from over as the bill now goes to the House of Lords, where it faces almost certain defeat.

Lord Wallace of Tankerness, the ex-LibDem MP and former Deputy First Minister, told The Herald: "There's been no substantial case to justify what the PM is wanting."

The day was characterised by passionate debate and high drama with the Prime Minister supposedly spending hours persuading MPs to back the move to extend pre-charge detention of terror suspects from the current 28 days to 42.

Jacqui Smith, the Home Secretary, secured the backing of Mohammad Sarwar, the Glasgow Central MP, who had been opposed to 42 days, after offering a compensation scheme for suspects held for more than the current 28 days but not subsequently charged.

Labour back bencher Austin Mitchell admitted he had intended to vote against the UK Government but changed his mind to "save Gordon Brown for the nation", adding that had the PM lost the vote he "would be on his way out".

David Davis for the Conservatives claimed the UK Government had lost the argument "hands down" and had "bought the vote".

Nick Clegg, the LibDem leader, said: "What we have seen is the sacrifice of principle in order to save the skin of a sinking Prime Minister."

Pete Wishart for the SNP said: "This is the worst of all outcomes for Gordon Brown. He can no longer rely on his own MPs for a parliamentary majority but is instead hanging by an Ulster thread."

Bill McVicar of the Law Society of Scotland commented: "I'm disappointed the UK Government has proceeded with the legislation against the advice they have been given by the DPP in England and the Lord Advocate in Scotland."

However, Tony McNulty, the Home Office Minister, insisted it would be "perverse" to interpret the vote as damaging to Mr Brown.

Rumours circulated of concessions to Labour back benchers on issues such as £1bn of injury compensation to miners. Supposed sweeteners to Northern Irish politicians included easing water charges in Ulster to the tune of £200m. No 10 denied any deals had been done.