In trying to find the history of this song, I came across this thread, and this posting from Hawker in a finishing songs thread- seems to fit here:

Subject: RE: What song do you finish with?
From: Hawker
Date: 17-Feb-01 - 07:37 PM

My Husband has just told me that Farewell shanty was discovered by the late Mervyn Vincent of St Issey, Padstow, Cornwall, in Plymouth Library whilst looking up old books about ships and sailing. It was either written in a book or a manuscript within the cover of the book. It is attributed as traditional, and was recorded by Johnny Collins on his album The Travellers Rest. According to the sleeve notes on that record, Johnny Collins learned it from Alan Molyneaux of Plymouth (Breakwater Folk Club?) It was always used to finish Mervyn's GREAT Stable Loft Folk Club at Wadebridge, Cornwall (sadly no longer in existence).............So there you have it - clever clogs my husband....unless you know otherwise.........

Lucy