Lap dogs no more!

After Parliament’s decision to reject taking part in any U.S.-led strike against the regime of Syrian President Bashar al-Assad, that victory cry rang out Friday from many quarters in Britain. For those who smarted at the memory of former prime minister Tony Blair — lampooned in the British press as President George W. Bush’s “poodle’’ — Friday marked the first day of a sweet new independence.

But Britons of another stripe awoke in a daze.

How had the Churchillian spirit of a nation suddenly turned into a Chamberlain moment, appeasing a tyrant? At great risk, they argued, was Britain’s outsize role in the world, a role it has earned since World War II by playing global deputy to America’s sheriff.

Despite official assurances on both sides of the Atlantic that the “special relationship” remained intact, these Yankophiles sensed that a bellwether moment had arrived.

“In 50 years trying to serve my country I have never felt so depressed/ashamed,” tweeted veteran British politician and diplomat Paddy Ashdown. “Britain’s answer to the Syrian horrors? none of our business!”

In Britain, prime ministers, and not Parliament, have traditionally been the deciders on military intervention. But the extraordinary events Thursday night appeared to signal a change.

It left Britons engaged in a bout of national soul-searching, with top officials saying the political earthquake in Parliament had raised a fundamental question about what kind of nation Britain ought to be. Would it remain a global force or begin to drift, as some suggested Friday, into a diminished state of splendid isolation?

Britain, a U.S. ally in the war in Iraq, might watch from the sidelines if Washington launches a Syrian strike and turns to France for a European stamp of approval. (Could we see the debut of “liberty muffins’’ a decade after the derisory “freedom fries”?)

For the United States, a less reliable Britain would be undeniably damaging. British military involvement was key to U.S. operations in Afghanistan and Iraq, with troops from these isles making up the single largest foreign force on the ground after that of the United States. In addition, Britain’s decision to sign on to U.S. operations lent them international legitimacy.

Yet Britain might have even more to lose. Its close relationship with the United States gave it a global footprint decades after Britain shed superpower status on its own. The relationship afforded not only diplomatic clout but also boosted British trade and industry around the world.

“I think this is more than a one-off decision. I think Parliament has set a precedent with the intention that it, not the prime minister, is going to decide whether or not we go to war in the future,” said Richard Kemp, the former commander of British forces in Afghanistan. “I think the British people, the many who say we have been America’s poodles for far too long, will now get much more used to this idea of saying no.”

During Thursday’s marathon debate, resistance appeared to be rooted less in straightforward anti-Americanism than in fatigue, distrust and frustration over the wars in Iraq and Afghanistan.

But also loud and clear was a newly pragmatic view that has only seemed to grow here since Parliament agreed to join Washington in launching a strike in Libya two years ago. The British military, skeptical lawmakers argued, should be reserved for action clearly and unquestionably in the national interest.

Although the Syrian opposition is viewed by many here as filled with elements just as bad as Assad’s forces, many British lawmakers thought it best to sit this one out.

The decision “has the potential to mark a very substantial alteration in the alliance between two countries, which call themselves their closest allies,” said Menzies Campbell, former leader of the Liberal Democrats, the junior partners in the Conservative-led coalition government.

But others laid Thursday’s debacle squarely at the feet of Prime Minister David Cameron — a Syria hawk who has long argued for a tougher stance on Assad.

Cameron failed, lawmakers said, to offer a clear mission statement, with few accepting his argument that bombing regime targets amounted to “not taking sides.” He also failed, the critics said, to learn the lessons of Iraq by appearing too eager to meet a rapid U.S. timetable for action, and he offered what several called flimsy evidence to back up claims of Assad’s hand in an alleged Aug. 21 chemical attack near Damascus.

Should Thursday’s decision herald a new day for a somehow dimimished Britain, not everyone here would be disappointed.

“I would be absolutely delighted that we really can relieve ourselves of some of this imperial pretension, that a country of our size can seek to be involved in every conceivable conflict that’s going on around the world,” Crispin Blunt, one of Cameron’s Conservatives who reject military action, told the BBC.

Karla Adam contributed to this report.