I have known "Billy Boy" since my childhood and even the great singers of the day were not to proud to sing such a song back in the radio days of the 1940's. It was not until coming across it Folk Songs of the British Isles
that I took it into my repertoire and sing it every now and then. Andrew Gant describes it as a Northumbrian sea shanty which was quite new to me - after all there is not much of a shanty feel about it. Any shanty that is supposed to be done quickly sounds a bit dubious to me.
It is a fine tune enough and the refrain of and me Nancy kittled me fancy, oh me charming Billy Boy
has a certain Jack-like quality that fits the mould.