The old Welsh tune, Llwyn Onn, known in the English-speaking world as Ash Grove, is over 200 years old, and has been used with the hymn lyrics "The Master Has Come" and "Let All Things Now Living." Regardless what title you know it by, it is a wonderful and beautiful tune.
This piece was originally written for piano, then expanded for organ, then rewritten in a different key for string orchestra, and now adjusted for use with string quartet.
The first violin plays sixteenth-note arpeggios nearly throughout, spelled in a couple of spots by the second violins, who have a rhythmic accompaniment most of the way through. The viola has the rhythmic accompaniment most of the time as well, but has pieces of the melody in a couple of places. The cello has the melody nearly all the way through.
FANTASIA ON ASH GROVE, for string orchestra by Tom Kirkland, comes in a pdf file of 571K, with a ten-page score, four two-page parts, and a license page, nineteen pages in all. Performance time should be approximately 3:40.