LONDON (Reuters) - A self-proclaimed straight speaker, Kemi Badenoch will bring a combative right-wing tone to the role of leader of Britain's Conservative Party, vowing a return to "authentic conservatism" to rebuild a party facing an uphill struggle to return to power.

Britain's first Black woman leader of a major political party, Badenoch is certain to shake up the Conservatives who suffered their worst election defeat in July under former leader and prime minister, Rishi Sunak.

In her sights is not just the left-leaning Labour government but also the right-wing populist Reform UK party led by veteran Brexit campaigner Nigel Farage, whose appeal drew traditional Conservative voters to his cause in July's election.

But the anticipated swing to the right under Badenoch, 44, could alienate the more moderate wing of the party and some voters who were won over by the centrist Liberal Democrats at the election, when Labour won a landslide victory.

"So here is what we are going to do. We are going to rewrite the rules of the game," she told the Conservative Party's annual conference in the central English city of Birmingham earlier this year.

"Some people say I like a fight. I can't imagine where they got that idea. But it's not true, I do not like to fight but I'm not afraid to fight," she said, pledging to go into combat against "left-wing nonsense" and for Conservative ideals.

Some critics say she is light on policy, but she says this is moot at a time when the Conservative Party is out of power. She called her leadership campaign "Renewal 2030" rather than using her name, a sign she believes the party needs time to recover to win power. The next election is due in 2029.

First elected in 2017 for Saffron Walden in southeast England, Badenoch was appointed trade minister in 2022, a rapid rise marked by a number of clashes with the media, celebrities and her own officials but also a surge in support in the then Conservative government who admired her no-nonsense approach.

TRUE CONSERVATIVE

Born in London and raised in Nigeria until 16 by her Nigerian father and mother, Badenoch says growing up in a place where "fear was everywhere" made her appreciate the safety of Britain and become a true defender of Conservative principles such as "free speech, free enterprise and free markets".

She says the administrations of former prime ministers such as Sunak and Boris Johnson gave up those principles in favour of an approach that meant the party "spoke right and governed left", handing votes to other parties.

She credits her father, a doctor who died in 2022, for teaching her to not be "afraid to do the right thing no matter what people said". 

Well-known Scottish actor David Tennant said in June he wanted her to "shut up" and wished she "did not exist any more" over her views on transgender and women's rights.

"I will not shut up," Badenoch responded on X, calling him "a rich, lefty, white male celebrity so blinded by ideology" that he couldn't see the optics of attacking the only Black woman in government.

She also faced a backlash when she said 5-10% of civil servants, or apolitical officials working in government, were "very bad" and "should be in prison" for undermining ministers - a comment her team said was a joke.

Comments that maternity pay was "excessive" and people should exercise "more personal responsibility" also raised eyebrows - again she said she had been misrepresented.

While some might see such slip-ups as a problem, Badenoch sees her straight talking as an asset, one she says has helped her work well in teams in government.

"A lot of people are not used to a politician who says it like it is," she said at the party conference. 

"That is what we need to do now in this age where everybody has a short attention span, you need people who can cut through very quickly and communicate our values clearly, I think I can do that."

(Reporting by Elizabeth Piper; Editing by Frances Kerry)

By Elizabeth Piper and Andrew MacAskill