It’s easy to forget just how massive Sinead O’Connor was back in the early 1990s. Her remarkable voice, forthright views, striking looks and of course THAT ‘Nothing Compares To U’ video made her a household name on both sides of the Atlantic.

But there’s also no doubt she was one of the most provocative and outspoken pop stars of her generation, then virtually ‘cancelled’ due to her very public stance on the Catholic Church. ‘Nothing Compares’, a superb new documentary from director Kathryn Ferguson, reinstates O’Connor to her rightful place as important artist and fearless trailblazer.

Ferguson nods to Julien Temple’s classic Sex Pistols doc ‘The Filth & The Fury’ by relying on O’Connor and her friends/collaborators to narrate her story off-screen, while using a huge collection of archive material and home movies – much of it previously unseen – to drive the narrative.

There are troubling details about her childhood shot through with some remarkable footage from the Magdalene Laundries. O’Connor escapes Ireland as soon as possible and we cut to the exciting London live music scene of the mid-to-late 1980s with spellbinding archive of her in her pomp, an artist who absolutely has to make music.

Then there’s a fair deal about her early dealings with the industry, and a lot of it isn’t pretty – to say that the male record-company paymasters do not come out of this period well would be a huge understatement. Interview footage of the time shows her to be softly-spoken, polite and intelligent, even during a Gay Byrne chat show in the presence of her parents.

And then we revisit the 18 months or so when O’Connor was virtually persona non grata in the USA, courtesy of her extraordinary appearances on ‘Saturday Night Live’ and the Bob Dylan tribute concert. If you haven’t seen these moments, I won’t spoil them for you, suffice it to say that if Pussy Riot carried them out today they’d be seen as cutting-edge protest/performance/art.

A minor criticism of ‘Nothing Compares’ would be that it ends very abruptly – we don’t hear much about O’Connor’s life and career post-1995, but no matter: it leaves recent docs about Bowie and Leonard Cohen in the dust. It’s moving, exciting, important and a must-see.