For self-confessed loner and cult superstar Daniel Johnston, the Union Chapel has become a sort of spiritual home. A gig here in 2007 spawned effusive praise and Johnston's first live DVD, and the mood is of admiration and unquestioning acceptance.

Watching Johnston, however, is uncomfortable. Relying on lyric sheets and haphazardly strumming his acoustic guitar, he's a big man imbued with the fragility of bone china. Unrequited love and mental-health issues remain an endless source of inspiration – "the same old songs of pain/ Gone public domain", as he puts it in opener Lost in My Infinite Memory – the little boy lost of his early-80s output replaced by a man with a thick voice scarred by experience.

"Are you with me so far?" Johnston asks. He's answered by cheers, but the Texan singer-songwriter always feels out of reach, even when he's at his most intimate, during Mask. A bridge of sorts, however, comes in his backing band, named by Johnston as "Texas Sea Lions" but who are in fact members of British Sea Power, rechristened for the night. Confident and approachable, they offer subtle, tender support, with Abi Fry's violin, in particular, wrapping itself lovingly around his broken vocals. The warmth of brothers Yan and Hamilton Wilkinson lifts the darkness of Love Enchanted and encourages a macabre sing-along on Funeral Home.

But 51-year-old Johnston remains devoted to older homegrown talent – the Beatles. Eulogised in an eponymous song and a cover of You've Got to Hide Your Love Away, the Fab Four also appear in the brilliant Rock'n'Roll/EGA, which sees Johnston briefly cast aside his vulnerability and embrace the quiet-loud dynamic beloved of famous fan Kurt Cobain.

Unquenchable longing, though, reappears with an encore of True Love Will Find You in the End; unique to the last, Johnston calls it "a special Christmas wish for you all", when it's actually a summation of everything extraordinary about him.