Richard Thompson, Shepherd's Bush Empire, London

White, middle-aged English men dominate a crowd who have packed this venue to bursting for a man barely known outside their tribe. Such cult adoration is perhaps all Richard Thompson can hope for now, as he follows a British pop path of lonely, eccentric uniqueness, and vital, hidden importance. The current re-release of his early work, with the Sixties folk-rock band Fairport Convention – co-founded by him at aged 17 – and with his former wife Linda in the Seventies, shows he was once a Dylan-like catalyst. He made the white, English ethnic music of folk listenable again, by introducing it to rock'n'roll, psychedelia, Indian classical sounds and, most lastingly, the repressions, rages, hopes and failures of his own white middle-class, baby-boom head. His wryly titled 1999 semi-concept LP Mock Tudor showed the perversity of his project – to make a conservative culture's roots grow.

That contradiction informs everything that happens tonight. The openness of the music Thompson plays is undeniable. Crashing in with the jaunty rockabilly of "Tear Stained Letter", much of what follows sees him reshape old songs with extended, exploratory blues-rock jams, reminiscent of Fairport Convention's improvisatory beginnings in psychedelic London, and the folk under- pinnings of even his heaviest contemporaries, Led Zeppelin. A fan of a certain age next to me shuts his eyes, the better to get lost. A gentle jazz tribute and Celtic reels are also played. But the nature of this gig as a reconvening of veteran fellow travellers, emphasised by Thompson's matey asides, means there is still an air of comfort and complacency, of a settled community being musically affirmed.

It is only when Thompson reaches back to the stark folk sounds that energised him in his teens that the deeper, sometimes disquieting emotions that keep him vital creep forth. On the current albumThe Old Kit Bag's "Outside of the Inside", with its chilling couplet "God never listened to Charlie Parker. Charlie Parker died in vain", his still cherubic face scrunches into a devilish, raging scowl. A stirring Iraq update of Phil Ochs's Vietnam war protest "I Ain't Marching Any More" prompts cheers, and a small rush for the bar (not all his fans belong to CND now). "A Love You Can't Survive" is a fresh folk story of drug-running and doomed romance, sung with classical conviction.

The most moving moment, though, is timeless and radical in a simpler way. "I Want to See the Bright Lights Tonight", sung on record by Linda Thompson in 1974, is about the aching need for the transcendence of a night on the tiles. As teenaged hope or middle-aged memory, it's life-affirming, beautiful pop – a heritage everyone can be proud of.