]
"Which provokes me to wonder whether large numbers of people from the north of England were employed on the Queensland cane fields. Does anyone know any more?"

I think the cane cutters, ie, those who were not Australian born, tended to be of Mediterranean origin. I don't think a lot of first generation Brits (Poms, if you like) ended up on the canefields...I think the 'mud' 'blood' problem is a case of eye rhyme...after all, 'bugger' and 'sugar' don't rhyme all that well either in any accent I can think of...

] "(Obligatory Jane Austen link: these were obviously the descendants of Mr Darcy's tenants in Derbyshire, and Mr Bingley's tenants in 'a neighbouring county'.)"

I shall retain your obligatory link just in case we get into trouble...