UK votes for action against ISIS: Will this time be different?

London (CNN) -- More than a decade after the Iraq war, when one million people took to the streets to protest against intervention, British lawmakers have again been grappling with their consciences.

In 2003, then-Prime Minister Tony Blair won a vote authorizing the use of force as part of a U.S.-led coalition to overthrow Iraqi President Saddam Hussein, but the war's chaotic aftermath left a bitter legacy.

Last year British Prime Minister David Cameron lost a vote to bomb the Assad regime in Syria amid public opposition to another war. Political commentators said the failed vote by Washington's long-standing ally put a brake on President Barack Obama's plans to punish the Syrian leader for allegedly using chemical weapons on his own people.

However, the task of Obama in building a coalition is likely to be made easier after Cameron easily won Friday's vote, by 524 votes to 43, authorizing the airstrikes against ISIS targets in Iraq. The opposition Labour Party supported the action against the Islamic militant group, despite doubts of some lawmakers on both sides of the House of Commons.

Opinion polls also suggest backing for action has grown following the release of videos showing the beheadings of western hostages. In August opinion was evenly split (37-36%), according to one YouGov poll, but is now markedly more in favor (53-26%). Polling by Comres conducted before the death of British hostage David Haines also found similar backing for airstrikes: more than half of those who took part in the survey backed action -- a rise of 5% in a month.

Cameron recalled Parliament after Iraq's Prime Minister Haider al-Abadi requested British military support in its battle against ISIS. Fighter planes from France and the United States have already started bombing in Iraq, but unlike in those countries the convention in Britain is for lawmakers to vote in Parliament before action is taken.

Veteran political commentator Robin Oakley said MPs were more in tune with the public than a year ago. "The degree of ISIS' brutality has changed a considerable number of minds.

"People who previously had doubts are now convinced that there is no alternative but force. Voices will be raised: some MPs believe that bombing ISIS may radicalize the population in areas that it controls. Local people who never liked the al-Maliki government and who may have been suffering ISIS may now offer it their support."

Oakley said it was the brutal videos that had likely won over lawmakers -- in contrast to the Syria vote. "Last year Labour couldn't support the action because MPs felt there was no conclusive evidence that al-Assad had used chemical weapons against his own people.

"MPs will worry about 'mission creep' when there is no obvious aim apart from to eradicate ISIS. Military action may destroy the leaders but it cannot eradicate ideas -- so the fear among lawmakers is that this intervention could be counter-productive."

Outside Parliament, there were also doubts about the military action. Protests took place in central London on Thursday, organized by Stop the War. The group's spokesman Ian Chamberlain said that while it was important to listen to public opinion, "once people start to see the results and start to reflect, I believe support will fall."

"Public support for military interventions in Afghanistan collapsed after the results of the bombing became clear. Bombing increases sectarian hatred of the west, and it's obvious that military intervention doesn't work. You can't destroy terrorism by bombing infrastructure. It just brings more terrorism."