This lovely but mournful song was written by Sandy Denny, an English folk singer who performed with Fairport Convention and who died in 1978 at 31 (drugs, of course). I think the best recorded version, though, was by Judy Collins on her eponymous album from 1969 (Denny was much less popular in America). Sadly, Collins’s version is not available on YouTube, but here’s Denny’s recorded version with Fairport Convention:
And have a listen to this one, with just Denny and a guitar.
From The Guardian:
Her best-known song, “Who Knows Where the Time Goes?”, along with Nick Drake’s “Fruit Tree” and John Martyn’s “Solid Air”, are products of a peculiarly English strain of blissful autumnal melancholy. As a lyricist she wove together the threads of English lyrical balladry, her songs variously recalling the lovestruck troubadour ayres of Thomas Campion, the antiquarian romanticism of Tennyson, Christina Rossetti’s windblown, regretful verse, and Thomas Hardy’s tragedies. As a voice – she has an unforgettable breathy huskiness – she connected the dots between the folk songs of Kathleen Ferrier and contemporary revivalists such as Briggs and Collins.
A live version from Judy Collins (2000), very different from the above but quite beautiful, is here.