Ari Up: Rebellious and confrontational singer with punk-reggae band the Slits

With her tumbling dreadlocks, mouthy righteousness and determined mission to mash down Babylon, Ari Up was the personification of 1977's Bob Marley song "Punky reggae party". Her later lifestyle was peripatetic, as she moved around the globe, but especially between London, Jamaica, Brooklyn and Los Angeles. Such journeying partially explains why Trapped Animal, the 2009 album by her group, the Slits, and the first since their 2006 reunion, should have been nominated in both the reggae and world-music sections for next year's Grammy awards.

The fact that she was only 19 when the five-year-old Slits split up masked the fact that Ariane "Ari Up" Forster had already lived a full and eventful life before the band even started. Her mother Nora Forster – who had long since split from her daughter's German crooner father – has been in a relationship with John Lydon since 1978, thereby making Johnny Rotten her stepfather: part of a continuum that had both Jimi Hendrix and members of The Bee Gees singing lullabies to this always almost feral warrior-child.

Ari Up's mother, a strikingly beautiful German blonde, was a promoter and player on the London music scene; she was also a publishing heiress. As the girlfriend of the guitarist Chris Spedding, Nora Forster was privy to his production of the Sex Pistols' first demos in May 1976, and therefore to a rapidly unfurling new musical world; Spedding had already encouraged Ariane's efforts at learning the piano.

Nora left Spedding, and her homes became refuges for assorted punk musicians including Joe Strummer, who gave Ariane guitar lessons. "He was like a guiding star", she told me in 2005. "He was like a brother to me. He never tried to come on to me, but was very protective and natural." (Later Ariane revealed that she was drink, drugs and sex-free until late in her teens.)

A synthesis of the militant feminism, strident anarchy and performance art of the zeitgeist, the Slits were formed by drummer Palmolive, previously a non-musician. Similarly creatively innocent was the 14-year-old Ariane Forster who, in the punk manner, renamed herself. "Her vocal stance," said Viv Albertine, who became the Slits' guitarist, "was almost like channelling sound." Dotted about Ari Up's increasingly reggae-influenced performances would be bird sounds and screams that seemed to derive from the darkest of nightmares. "Punk was meant to be honest and true, and that was Ari's voice," added Albertine. "It wasn't about entertainment, but moving the audience or waking them up. But it could be sexy and melodic as well."

Tessa Pollitt, who would soon become the Slits' bass-player, saw the group play at a Dalston cinema. "Ari wore a long mac which she kept flashing to reveal Union Jack pants worn over leggings. I'd never seen anything like it: it was very sexual. She had a totally unique look that has influenced Bjork and Madonna. She had an extremely rebellious spirit."

So rebellious was Up that she was prepared to play the occasional absurdist wildcard. "She pissed onstage," recalled Albertine. "She squatted down at the Music Machine, and pissed onstage. In the 1970s girls were supposed to be shy and wear pretty dresses. I think she was a real revolutionary."

Enrolled at liberal Holland Park comprehensive, Ari Up was allegedly attending the school while the Slits were traipsing around Britain in May 1977 as part of The Clash's White Riot tour – the writer Caroline Coon described her as "a Lolita-type". Their manager was Don Letts, the Rastafarian film-maker. As part of a cultural-studies course which would include indulging Up's desires to visit Jamaican blues shebeens, to study dancers, Letts took her to a meeting of the 12 Tribes, a branch of Rastafari.

When she endeavoured to take a lick on a ceremonial ganja chalice, she and Letts were cursed by the dread elders: this was no business for a woman. "She responded with some very choice language", Letts remembered. "We left: it was all quite frightening. Ari totally destroyed men with her conviction: the women of today with all this celebrity bullshit in which people are as deep as make-up could learn from her."

Famously, the Slits were the last original punk act to be signed, by Island Records. "They were unmanageable and scared the music business, and Ari frightened everybody," Letts said. In 1979 their masterly album Cut, produced by the reggae maestro Dennis Bovell, was released, to no great sales. Endlessly confrontational, the sleeve art consisted of a shot of the three girls, naked except for strategically placed mud and loincloths. At the end of 1981 they released a further album, Return of the Giant Slits; shortly after, the Slits split up.

For a time, Ari Up worked with The New Age Steppers collective under the auspices of Adrian Sherwood. But soon she moved to Jamaica, giving birth to twin boys, Pablo and Pedro, fathered by her boyfriend, Glenmore "Junior" Williams. After the relationship failed, she gave birth to another son, Wilton, in 1994. Tragically, the boy's father had been shot dead by the time he was born.

Although blessed with the finances for an uptown lifestyle, Ari Up preferred the edginess of the semi-ghetto area of Maxfield Avenue, where gunshots often ring through the air. Known in Jamaica as Madusa, she was a familiar figure at dancehall events across the island, the musical style informing her 2005 solo album, Dread More Dan Dead, as well as Trapped Animal.

Touring again under the group's name, with Tessa Pollitt and Hollie Cook, the daughter of Sex Pistol Paul Cook, her behaviour on their last set of dates was somewhat irascible; this was a consequence, it now seems, of an illness Ari Up had been doing her best to ignore. She died of cancer.

Chris Salewicz

Ariane Daniele Forster (Ari Up), musician: born Munich, Germany 17 January 1962; three sons; died Los Angeles, California 20 October 2010.