There are other fine songs on Martha Wainwright's 2012 album, Come Home to Mama, but Proserpina, the one that gives the disc its title and the last completed work by her late mother, Kate McGarrigle, looks set to become a standard of the modern "folk" repertoire that identifies her to subsequent generations, as Music For A Found Harmonium does the late Simon Jeffes of Penguin Cafe Orchestra.

In what was otherwise a solo set with acoustic guitar (save the a cappella off-mike encore of Piaf's La Vie En Rose), Wainwright was joined for Proserpina by festival director Donald Shaw on harmonium and Aly Bain on fiddle for what were the most moving moments of a very fine show that consistently referenced her family, in the way that the remarkable Wainwright clan often does.

So while she didn't actually shed her pants, as her brother Rufus did at his recent Glasgow show, she was happy to chat about what they hid, and the birth of her son, to whom the closing song of the disc – and her set proper here – Everything Wrong is addressed. The third cover of the night, Tower of Song, came from the catalogue of Leonard Cohen and although she claimed to be daunted by the history of it, the fact it was written by her niece's grandfather surely entitles her to sing it.

Then there's that independently minded left leg of hers, its movements identical to those of her father Loudon, name-checked as an influence when she became lost in a sequence of chords and busked her way back. His diva daughter brought another memorable show to a festival in which the family has booked a permanent place.

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