Britain's Cameron furious after biggest party revolt
* PM Conservative party rebels force government climbdown
* Conservatives becoming increasingly rebellious
* Rebellion threatens PM, coalition government
LONDON, July 11 (Reuters) - A revolt against British Prime Minister David Cameron within his own Conservative party has damaged his authority this week, threatening an already fragile coalition government at a time of growing public anger with his leadership.
In a dramatic move late on Tuesday, 91 rebel Conservatives forced Cameron to drop a crucial vote on reforming parliament's upper chamber, or the House of Lords - a key demand of his Liberal Democrat partners in coalition government.
Lawmakers have described a furious Cameron confronting the rebellion's leader late at night at Westminster a fter the biggest revolt against his leadership since he come to power in 2010.
If Cameron fails to keep his promise on the House of Lords, Lib Dem lawmakers may in turn decide to oppose Conservative policies, crippling the government's legislative agenda and placing the increasingly frayed coalition under further strain.
Conservative rebels gave different motives for their dissent, but restiveness within Cameron's party is only likely to grow as calls mount for the government to take a stronger stance on Europe, and as the economy continues to falter.
The explosive issue of whether to hold a referendum on Britain's ties with Europe - a thorny point that has in the past helped fell previous Conservative governments - triggered a major Conservative rebellion late last year.
Members of parliament described dramatic scenes after the vote on Lords reform was pushed to the autumn at the last minute on Tuesday to avoid what would have been the coalition government's first major parliamentary defeat.
"Just witnessed a very angry PM lambasting Tory (Conservative) MP Jesse Norman. Finger pointing and prodding towards Mr. Norman. Not very prime minister like," opposition Labour lawmaker Karl Turner said in a tweet from the scene.
One newspaper report of the incident quoted a Conservative lawmaker as describing Cameron's behaviour as "disgraceful".
An aide to Cameron said however there was no major argument, only that the prime minister was "rightly annoyed".
Conservative lawmaker Peter Bone called Tuesday's rebellion "another nail" in a coalition government whose mandate is to fix Britain's ailing economy and tackle its big budget deficit.
"The Liberal Democrats and Conservatives agree on virtually nothing and to keep us together now is pointless because we've put in place all the measures to solve the economic crisis," he told Reuters.
TASTE FOR BLOOD
Cameron's leadership is being increasingly questioned after a string of policy reversals, a return to economic recession and his embarrassing ties to Rupert Murdoch's News Corp media empire, generating bad headlines and low poll ratings.
Unluckily for Cameron, who came to power at the head of Britain's first coalition government since World War Two, ministerial portfolios shared between two parties leave few government posts with which to induce more loyalty among rank-and-file lawmakers.
"You might as well be true to your principles, because there's no reason to modify them for collective responsibility. You're never going to be in the government anyway," Bone said.
In a dangerous sign for Cameron, dissent has spread beyond the usual suspects - the so-called "awkward squad" - to party stalwarts and usually loyal new members.
"Once people get the taste for blood, they tend to rebel rather more than they did before. So whilst this might be a rebellion on a particular issue, it will encourage some people who haven't rebelled before to do it again," said Sussex University professor Tim Bale.
For some, a series of government U-turns in recent months on taxes and other issues has increasingly given the impression of a more malleable leadership, emboldening Conservative rebels.
"The government having changed course on a number of policies will undoubtedly have weakened confidence in the calibre of the government's judgement, or in their tactics," Conservative lawmaker Julian Lewis told Reuters.
Charlotte Leslie, one of the usually loyal 2010 intake of Conservative lawmakers, said many in her generation had entered politics at a time of deep public cynicism, and were therefore more wary of pragmatic or cynical political compromises.
"Because of transparency and all those things that go with an open social media, we've lifted the lid on the sausage factory .... People demand now to see things and say that doesn't look very nice, and I think our intake is particularly aware of that," she said, explaining her decision to rebel.
There are no credible challengers to Cameron's leadership for now, but some say the rebels are playing a long game, and positioning themselves with an eye to the 2015 general election.
"Clearly there are a number of people in the Conservative Party who are prepared to cock a snook at Cameron, which suggests that they think either that he's too weak to make a difference to their careers or that he won't be around that long," Bale said.