Who is Britain's likely next prime minister Keir Starmer?

UK Labour leader Keir Starmer is a former human rights lawyer turned-state prosecutor whose ruthless ambition and formidable work ethic look set to propel him to Britain's highest political office.

The 61-year-old, whose unusual first name was his socialist parents' tribute to Labour's founding father Keir Hardie, is also the centre-left party's most working class leader in decades.

"My dad was a toolmaker, my mum was a nurse," Starmer tells voters often, countering depictions by opponents that the one-time "lefty lawyer" is the epitome of a smug, liberal, London elite.

With his grey quiff and black-rimmed glasses, Starmer remains an enigma in the eyes of many voters, who will likely hand him the keys to 10 Downing Street in a general election on July 4 nonetheless.

Detractors label him an uninspiring opportunist, but supporters insist he is a managerial pragmatist who will approach being prime minister the same way he did his legal career: tirelessly and forensically.

"Politics has to be about service," Starmer said in a campaign speech on Monday, repeating his mantra to put "country first, party second" following 14 years of Conservative rule that brought five prime ministers.

Sometimes appearing uncomfortable in the spotlight, the football-daft Arsenal fan -- who came to politics late in life -- has struggled to shed his public image as buttoned-up and boring.

But the married father-of-two is said to be funny and loyal in private, while his route to the cusp of the premiership is more interesting than he is given credit for.

- Mother's death -

Born on September 2, 1962, Keir Rodney Starmer was raised in a cramped, semi-detached house on the outskirts of London by a seriously ill mother and an emotionally distant father.

He had three siblings, one of whom had learning difficulties, and his parents were animal lovers who rescued donkeys.

"Whenever one of us left home, they replaced us with a donkey," Starmer has joked.

A talented musician, Starmer had violin lessons at school with Norman Cook, the former Housemartins bassist who became DJ Fatboy Slim, and attended a prestigious London music school at weekends.

After legal studies at the universities of Leeds and Oxford, Starmer turned his attention to radical causes, defending trade unions, anti-McDonald's activists and death row inmates abroad.

He is friends with human rights lawyer Amal Clooney from their time together at the same legal practice and once recounted a boozy lunch he had with her and her Hollywood actor husband George.

"There were quite a lot of empty bottles by the end of the evening," Starmer remembered.

In 2003, he began moving towards the establishment, shocking colleagues and friends, first with a job ensuring police in Northern Ireland complied with human rights legislation.

Five years later, he was appointed director of public prosecutions for England and Wales by the then Labour government.

Between 2008 and 2013, he oversaw the prosecution of MPs for abusing their expenses, journalists for phone-hacking, and young rioters involved in 2011 unrest across England.

He was knighted by Queen Elizabeth II, but rarely uses the prefix "Sir", and in 2015 was elected as a member of parliament, representing a seat in left-leaning north London.

Just weeks before he was elected, his mother died of a rare disease of the joints that had left her unable to walk for many years.

- Rebellion -

In 2021 he broke down in tears in a TV interview as he described how her agonising death "broke" his father.

Just a year after becoming an MP, Starmer joined a rebellion by Labour lawmakers over left-winger Jeremy Corbyn's perceived lack of leadership during the EU referendum campaign.

It failed, and later that year he rejoined the top team as Labour's Brexit spokesman, where he remained until succeeding Corbyn in April 2020.

Starmer has since shown ruthlessness by purging Corbyn from the party, moving it back to the centre, and making moves to root out anti-Semitism that had made Labour unelectable.

The left accuses him of betrayal for dropping a number of pledges he made during his successful leadership campaign, including the scrapping of university tuition fees.

But his strategic repositioning of Labour to put it back on a path to power is indicative of a constant throughout his life: a drive to succeed.

"If you're born without privilege, you don't have time for messing around," Starmer once said.

"You don't walk around problems without fixing them, and you don't surrender to the instincts of organisations that won't face up to change."