Not a waltz but a slow air. Last of four similarly-named airs published in O’Sullivan. Carolan: life, times and music of an Irish harper vol.1 p.179-180. Indexed in the new Vaughan Williams Memorial Library site http://www.vwml.org.uk/search.
On Derek Bell’s album Carolan’s receipt (Shanachie, 1987. https://thesession.org/recordings/3056) this is the third tune in the Bridget Cruise set.