Hi Sminky,
Anything I can be looking for regarding his stay in Hull in 1861?

Artful codger and I are working on Harry Clifton's sheet music at the moment. A contemporary of JBG, he seems to have other similarities with HC.
I have several copies/originals of JBG's sheet music that I can post when we've finished the Clifton material.

Originals
John Barleycorn is a Hero Bold
The Men of Merry England
The Same Old Game (sung by Sam Torr)
Ten Thousand Miles Away

Copies
Cockles and Mussels
Down in a Coal Mine

I have seen a sheet music original of 'When Johnny Comes Marching Home' with a brightly coloured litho of soldiers. It was for sale at the music/book shop down Bell St, Edgware Road in London, but too expensive for my pocket, about £15 if I remember rightly.

I also have the words of others of his songs on broadsides.