I've just looked up Suo Gan in one of our better reference books for Welsh folk song. For those interested in history ...

it was copied originally from a manuscript found in Llanberis (N.Wales) and first published around 1904. The current one is a variation on an older one (same name) published in 1794. In 1820, one of our big-time bards wrote, "It is very probable that Storace took his Lullaby in the Pirates from this tune." ???

Anyway ... there's a bit more background for you...

sian