Sinéad O'Connor, LSO St Lukes, London

The manner and the speed with which Sinéad O’Connor veers between impishly poking fun at herself and her material, and delivering it with scorching force, is bewildering. For instance, with the “The Healing Room”, a tender song about a spiritual quest for inner peace, she cracks jokes about Mr Blobby during the intro and then changes the opening line to “I have a universe inside me… and a cucumber.” What’s extraordinary is that despite often sending herself up in this way, she can immediately slip back into singing so fiercely and persuasively that everything flows. The comedy moments merely add levity and punctuation.

The gig is semi-acoustic (the keyboards are electronic) and O’Connor performs barefoot on a carpet between guitarist Robbie McIntosh and keyboard-player Graham Henderson, her sole accompaniment. She looks slimmer, happier and more mischievous than when I reviewed her last March. Her petite form is clad in tight black jeans and a black T-shirt that proclaims “Jahrastafari”, and her hair is shaved down to stubble. The first half of the set is devoted to last year’s How About I Be Me and You Be You?, an album whose success was undermined by the singer’s mental health problems. After a small flurry of concerts, she went to ground for most of 2012.

While unavoidable, this was a shame as the album is one of her best, as is demonstrated when she confidently opens with three of its feistiest pieces: John Grant’s vitriolic “Queen of Denmark”, which she bites into with relish, the superb junky ballad “Reason With Me”, and the jolly, loved-up, self-affirming “4^th and Vine”. Prior to the latter she casts aside the acoustic guitar, which looks gigantic against her frame, and says “I don’t know if they let you dance in this kind of place… but they let me,” and jigs about enthusiastically. “This kind of place” is LSO St Luke’s, an 18th century church intact on the outside but transformed within into a very modern amalgam of red brick, wood panelling and metal, a dream acoustic venue.

She can turn the mood utterly in seconds in a way that should be the envy of any artist As the set moves along, O’Connor seems increasingly unsure of her musical skills and often sings - literally sings - out requests to McIntosh as to whether she’s playing correctly, or asks how a song is going to conclude. At one point she even closes a number by singing beautifully, “Sinead fucks up her own song, even though it only has two chords.” She may make such mistakes but nothing is really fucked up – O’Connor holds the attention completely, and everything about her appears to be from the heart and in the moment. I can take or leave a lot of O’Connor’s recorded work – it often has a somewhat bland, middle-of-the road production – but in the live arena she is simply mesmeric.

Throughout the gig there is a female heckler, positive, excited, possibly drunk, an über-fan. She becomes increasingly vocal, but O’Connor rolls genially with it and responds to one request by leading the audience in Lionel Bart’s Oliver sing-along standard “Consider Yourself”, before stopping and announcing, “That’s another gig.” Then she bursts into a heart-rending “Nothing Compares 2 U”. She can turn the mood utterly in seconds in a way that should be the envy of any artist.

The most ballsy song is a driven reading of “Jackie” from her 1987 debut album The Lion and the Cobra, which whips things up after a series of downtempo numbers. Midway through the encore she then dismisses her band with the line “it’s time for you two to fuck off,” before gigglingly relenting and offering the pair up for applause. Then she closes with her Rastafarian version of “Psalm 33” and a brief lullaby song which she tells us she learnt from some monks. She closes this last with a drowsy, “Zzzzzzzz…” and then she’s gone.

I’d recommend anyone who has never seen this woman in concert – even if they think she’s not their bag - to take any opportunity to catch her. Onstage, Sinéad O'Connor is truly one of the greats.

Sinead O'Connor performs an acoustic version of "Nothing Compares 2 U" on French TV show Taratata