Liberty in the UK got another thwacking yesterday, as the Labour government passed its bill to hold terror suspects for 42 days without charge. Three cheers then for David Davis, who today resigned as Conservative Shadow Home Secretary in protest.

Davis did not consult David Cameron, his party leader, before announcing the news and insiders think his resignation might spark a crisis in the party. This is mysterious, because Cameron also opposed the 42-day bill. But Davis is rumored to have been frustrated that some of his Tory peers were frightened about being perceived as “soft on terror”.

When Michael Howard stepped down as head of the Tories in 2006, Davis–a sort of Tory Jim Webb: ex-SAS and tough as tungsten–was expected to take over. But the smoother, more polished Cameron outmanoeuvred him.

Cameron has been widely hailed as that rare thing: a successful Conservative leader. But Davis’s resignation could bring out considerable discontent within the Tory ranks.