Everybody knows Come Write Me Down, and everyone got it from the Copper family of Rottingdean, who deserve a blog entry far longer than I feel like typing on an iPhone.
The last verse isn’t from the Coppers though - there’s no smut in the Coppers’ Book - Gill heard Bill Elliott singing it and he credits his grandfather, Jack Elliott. The Elliotts of Birtley are worth a longer blog entry too, or seek out Pete Wood’s book on them.
It does feel odd to hear this without any harmonies. Come Write Me Down is so well known that folk club audiences don’t just join in on the repeats, they join in with the verses too. Which makes it a very good “first song ever” to sing out. If you’re a bit nervous or you forget a line your audience will carry you through.