The British singer-songwriter Sandy Denny (1947-1978) was just 20 years old when she first recorded "Who Knows Where the Time Goes" — her masterfully tender ballad about total immersion in love — in July, 1967, at a makeshift studio set up in a moviehouse in Copenhagen, Denmark. Denny was then — briefly — a member of a new English folk group, the Strawbs, singing harmonies and occasional leads in songs written by founding singer-guitarist Dave Cousins. The Copenhagen sessions ¬— genial, acoustic romance, with group vocals that suggest Judy Collins hooking up with the Rubber Soul Beatles — would not come out until 1973, after Denny became an electric-folk star with Fairport Convention and the Strawbs had matured into a polished fusion of progressive rock and antique British balladry. But All Our Own Work (Witchwood Media), reissued with a dozen outtakes and demos, has a durable allure, especially when Denny comes to the fore. The youth is evident in her bright rippling voice; she has not yet ripened into the deeper supple drama of her crucial Fairport records, Unhalfbricking and Liege and Leaf. Denny is, though, majesty in the making, in Cousins' "Tell Me What You See in Me" and her solo vocal in his own sensual memoir, "Two Weeks Last Summer."