"Maggie O' Ham" is a Shetland single jig in 6/8 or 12/8 time in A Major. The traditional fiddle tuning for this is AEae.
Tom Anderson (1978) says the melody was probably used as an alternative tune for the dance "Shaalds O' Foula"/"Foula Shaalds" (also known as "Da Foula Reel"). He says "He comes fae Foula bit wha Maggie o’ Ham wis ah’m never fun oot." ("It comes from Foula but who Maggie o’ Ham was, I never found out.")
It was printed in Anderson & Swing's Haand Me Doon da Fiddle (1979).
It was recorded Aly Bain & Tom Anderson on Shetland Folk Fiddling, vol. 2 (1978) and Aly Bain & Ale Möller on Fully Rigged.