The week-long series of charity concerts for Mencap are proving a major draw, not just for music fans but for bands as well. Stars more accustomed to playing to ant-like audiences in arenas seem inspired by the opportunity to reduce their back catalogue to its bare bones, with an acoustic set within the dramatic architecture of Islington's Union Chapel.

Even U2 had a brief go on Friday, and last night fellow Irishmen Snow Patrol seemed more intimidated by the full pews before them than any stadium. "You could be witnessing the end of our career," joked singer Gary Lightbody nervously.

To try to counter that exposed feeling, he had brought with him 15 other musicians, a multitude of string and horn players who made this show much more than just the band's normal set in anaemic form.

In what was their last gig for some time, they took the opportunity to leave their rockier favourites at home and instead augment the big ballads with three covers and a handful of original rarities.

Fifteen Minutes Old, apparently never before played live and written when Lightbody was 18, had a lovely yearning guitar line, though the singer mocked his own simplistic teenage lyrics. It came from Snow Patrol's first album, Songs for Polarbears, which makes it a real obscurity since the album most people think is their first is actually their breakthrough third.

The fragile xylophone twinkling of newer song You Could be Happy also made its live debut in appropriately hushed surroundings. Then there was the charming country shuffle of Just Like Christmas by Low, and two throwaways perfect for the evening's novelty covers-obsessed host, DJ Jo Whiley - About You Now by the Sugababes and I Am An Astronaut, written in 1972 by Kim Wilde's 12-year-old brother Ricki.

Lightbody, wearing a white tie tucked into a black jumper that looked rather like a vicar's dog collar, made too many lame God jokes in this blessed venue, but when he stopped rambling and sang, his rich voice had real spirit. There can be few better places to hear his band's two megaselling ballads, Chasing Cars and Run, here refreshed by lush new string arrangements that transformed them into even more powerful tearjerkers.

That's it for Snow Patrol for the time being, with a Lightbody solo album rumoured and a new band release vaguely pencilled in for Christmas 2008. This show was something lovely to remember them by.

Union Chapel, N1. Tonight: Kate Nash; tomorrow: The Enemy; Weds: Keane. 0870 042 8655, www. littlenoisetickets.trinitystreetdirect.com