"According to Nigel Gatherer's Traditional Music Pages the title is actually PLUMBERS AND JINERS."

Mea Culpa! (Latin for 'Jings! Ah'm awfy sorry, Jimmy!"

NB: Reading Watt's discography on Nigel's site I note with interest, (and purely for completeness), that on 'Watt a Night' the song is listed as written by Watt himself but on '5,227,706 Scotsmen Can't Be Wrong!' in 1971, it is given as 'Trad: arr Nicholl.