Winston Churchill is credited with once saying "Kites rise highest against the wind, not with it." The current British prime minister may illustrate the opposite, as Theresa May flies high, facing an opposition akin to a gentle breeze.

May was grinning from ear to ear Friday. And no wonder. Her Conservative Party had just scored an unexpected and almost unprecedented byelection win.

'This is an astounding victory.' - British Prime Minister Theresa May

"This is an astounding victory," she said, surrounded by supporters in Copeland, a northwest England constituency that, until a day earlier, had been held by the Labour Party since 1935. What's more, the Tory leader told the assembled crowd, a ruling party hadn't taken a seat from the opposition in a byelection for 35 years. 

It's the latest example of the May Conservatives' dominance on the British political scene. While an effective opposition positions itself as a potential alternative government in the minds of voters, the current opposition "is extremely weak," said John Curtice, a politics professor at the University of Strathclyde in Glasgow. The Labour Party hasn't been this unpopular as the official opposition since 1983, Curtice said.

Labour, led by Jeremy Corbyn, did hold its seat in a separate byelection in Stoke-on-Trent Central on Thursday, but it was seen as a win over the U.K. Independence Party (UKIP) rather than the Conservatives. 

94630577

UKIP leader and Stoke-on-Trent Central candidate Paul Nuttall arrived at a byelection polling station Thursday expecting to have an easy ride in the city dubbed 'the Brexit capital of Britain.' He lost. (Christopher Furlong/Getty Images)

UKIP — among the most vocal supporters of the campaign to have the U.K. leave the European Union — sent its new leader, Paul Nuttall, to claim the seat, expecting the anti-EU party would have an easy ride in the city dubbed "the Brexit capital of Britain."

It wasn't so. Within hours, an embarrassed Nuttall was facing questions about his future as leader, and UKIP's future as a party. "We are not going anywhere. I'm not going anywhere," he told reporters.

He wasn't the only opposition leader trying to reassure his party. On Friday afternoon, Corbyn travelled to Stoke-on-Trent and delivered a minute-long speech to local volunteers. He thanked them for their work and said Labour's win in the constituency showed that "hope triumphs over fear."

Repeatedly pressed by journalists for comment on his party's defeat in Copeland, Corbyn instead attacked the reporters. "The one thing I've learned about the media is you're incredibly rude to each other," he said before walking off.

Labour 'in deep trouble'

To an observer, it may look as though Corbyn feels he's getting an unfair shake. Rarely does an entire week go by without the British press musing about how soon he may quit his job or how badly Labour would fare in a general election under his leadership. On Friday, London's Telegraph projected Corbyn's party would be "obliterated" and May would be awarded with a "fat majority" if British voters were called to the polls now. Labour "is in deep trouble," Curtice said.

The U.K.'s vote to leave the EU, initiated in 2015 by Conservative Prime Minister David Cameron, may have played a role in rendering the opposition rudderless.

Although Corbyn campaigned against Brexit, he's done nothing to stop it — unwilling to counter the apparent will of the majority. He even instructed Labour MPs to vote to allow the prime minister to trigger Article 50, formally beginning the U.K.'s divorce process from the EU. And the referendum result has left Brexit boosters UKIP struggling to find a new raison d'être.

'The debilitation of the Labour Party is the facilitator of Brexit.' - Tony Blair, former British prime minister

With current opposition leadership floundering against the May government's Brexit plans, a cast of unlikely characters has re-emerged to challenge her.

Last week saw the attempted political resurrection of former prime minister Tony Blair. A decade after leaving office, he presented himself as the saviour of Britain in the EU, urging Remain voters to "rise up." "The debilitation of the Labour Party," he said about the organization he once led, "is the facilitator of Brexit." 

94550195

Former British prime minister Tony Blair, speaking at a pro-EU event on February 17, 2017, in London, said people voted in the Brexit referendum without knowledge of the true terms, and urged people to change their minds and rise up against Brexit. (Carl Court/Getty Images)

And for watchers of British politics there are more flashbacks to years past. Former Labour leader Ed Miliband has returned to the spotlight, emerging as the party's go-to critic of Donald Trump, appearing on television at a frequency unseen since his trip to the backbenches.

Even the Liberal Democrats, greatly wounded in the 2015 general election, have been trotting out the former deputy prime minister, Nick Clegg, to serve as Brexit critic. Whether those are signs of creativity or desperation, opposition parties appear eager to test out tricks before the next general election, expected in 2020. 

For now, as May steers the U.K. toward Brexit, she's likely feeling the wind blow in her sails rather than in her face.