Hello from New Zealand with my experience of 'Soon May the Wellerman Come'. The 1972 'New Zealand Folksongs: Song of a Young Country' LP and songbook were the first accessible collection of songs of early European contact, immigration and settlement for young musicians like myself to call on. For Neil Colquhoun it was the culmination of fifteen years of researching, recording, radio programmes and concerts all featuring New Zealand folksong.   
On the recording, 'Soon May The Wellerman Come' was sung by Tommy Wood. In response to the world-wide interest and in preparation for a radio programme on New Zealand folk I contacted Tommy. From the source... 'From memory I came across the poem in a book on NZ sailors and as a folk singer in those days was collecting songs to sing at the clubs. I had mentioned it to Neil Colquhoun, then a fellow club member, who knew about it and hummed a rough guide to the tune. It became my song at the time, singing it at various clubs around until finally singing it on the album 'Songs of a Young Country'...unfortunately I have not got the book anymore. All I can remember was stories connected to whaling, exploring NZ and immigration ships, containing personal letters of life on board these ships, including poems...black and white sketches of ships, sailors etc...it was fairly old then [late 1960s?]! My late wife Margaret was a librarian and she brought it home after it had been removed off the shelves...The Wellerman was an actual poem in the book but not quite in rhyme I had to adjust some of the words to fit the tune that Neil and I managed to put together..'.

There's the mission. Find the book that 'Soon May the Wellerman Come' came from.

Mike