The Fantasia on Welsh Nursery Tunes is a composition for symphonic orchestra, based on traditional Welsh nursery tunes and lullabies, composed by Grace Williams in 1940. Although not typical of Williams' work it brought her to prominence and is the composer's most popular work. I had a thorough grounding in Welsh airs and Welsh folk songs when I was a child and teenager, and they found their way into some very early works, now withdrawn, and of course into the Fantasia. — Grace Williams, Interview with Heward Rees