Last week, Martha Wainwright kicked off a UK tour at Cadogan Hall in London. Pete Townshend came up out of the audience to perform with her during the last two songs of the set. They covered Joni Mitchell’s “Both Sides Now” to start, and then performed Wainwright’s own “Factory,” off her 2005 self-titled debut album. Wainwright and Townshend have performed the latter track a couple times before, once in 2006 and once in 2007. Watch video from the show below.