Thanks Rosie
Can't see much that fits back in Scotland in the earlier censuses. From 1871, for any Joseph Turnbull born in the 1850s in Scotland, we have:
Joseph aged 12, born in Glasgow, with parents Joseph and Elizabeth. Living in Glasgow.
Joseph aged 14, born in England, adopted by a Mary Davidson, living in Glasgow.
Joseph aged 14, born in Langholm, the son of Thomas and Ann discussed above.
Joseph aged 12, born in Morebattle, son of Jane (husband William), living in Channelkirk.
Couldn't see anything that would fit in England for him in 1871.
In 1861, same Josephs as above, except:
English born Joseph does not show.
A further Joseph born c.1850. Son of a Thomas and Helen. Born and living in Cavers.
Not much to work with really...

Monica