Daniel Johnston & The Texan Sea Power (British Sea Power), Union Chapel, London

“Hi, how are you these days?” begins Daniel Johnston, in 'Lost in My Infinite Memory'.

It's a question he's been asking ever since his sixth album, 1983's Hi, How Are You. That was illustrated with one of his cartoon frogs, later famously seen on a T-shirt worn by Kurt Cobain, giving this American outsider who recorded cassettes in his parents' basement a huge shot of publicity. Johnston – now middle aged, paunchy in jogging bottoms – was given another boost in 2006 by a documentary exploring his struggles with mental illness, but he still remains a cult figure.

And he surely always will. For the first three tracks, Johnston bashes away at an odd little headless guitar, making a rackety noise over which he sings brief ditties, with typically love-sick or self-loathing lyrics of child-like simplicity and surprising perceptiveness. Although these reach you plain and clear, his voice still exhibits that strained, tremulous, lisping fragility.

It is, being honest, something of relief when Johnston is joined by indie-folk band British Sea Power – tonight billed as The Texan Sea Power and referred to as his “Texan Sea Lions”. They bring melodic guitars, viola and drums to bear on his back catalogue, finding satisfying pop hooks. BSP's Hamilton Scott Wilkinson pounds out organ chords, recalling the wheezy tones of the cheap chord organ of Johnston's records, and suddenly a strange raw power takes hold - even as Johnston's two-handed grip on his microphone stand shakes violently.

He isn't the easiest person to play with, although BSP mostly look like they're having terrific fun. And after all, it is that rough hewn charm and creeping melancholia that Johnston's fans are looking for - and they cheer him all the way, sometimes literally, as when he begins 'Walking the Cow'. This is given a Gothic minor key creepiness that suits the venue, continued on 'Love Enchanted', all shivering cymbals and plaintive viola.

Johnston's always been a massive Beatles fan, and we get not only a remarkably assured-voiced cover of 'You've Got to Hide Your Love Away' – an obvious fit, riddled with paranoia – but also his tribute, 'The Beatles': “like a magical fairy tale that's hard to believe/But it really did happen” he sings with sweet sincerity. Given the warmth and admiration this naïve, unwell, unconventional but singularly talented individual continues to inspire, more than 30 years into an unlikely rock career – well, Johnston could almost be singing about his own fairytale.

SETLIST

‘Lost in My Infinite Memory'

‘There is a Sense of Humor Way Beyond Friendship’

‘Mask’

‘Don’t Let the Sun Go Down on Your Grievances’

‘Casper the Friendly Ghost’

‘Speeding Motorcycle’

‘Walking the Cow’

‘Love Enchanted’

‘Mountain Top’

‘You've Got to Hide Your Love Away’

‘Fish’

‘The Beatles’

‘Funeral Home’

‘Rock’n’Roll EGA’

‘Devil Town’

‘True Love Will Find You in the End’