to add some further details he shows up in the 1851 census Oxnam, Roxburgh, GROS reference 802/00002/00008 as part of the family of a John Douglas and Elizabeth.
He has brothers Lancelot, William and Robert from the Oxnam Parish Registers (GROS reference 802/ 0020 0063:, Oxnam, Roxburgh)
They all show up in the 1861 census return for Oxnam again with the brother of John Douglas, Lancelot. Obviously the son of John is named after John's brother.
The Oxnam Parish Registers available via the GROS only seem to give the name of the father John when recording the births of John, Lancelot, William, etc.. The census returns don't appear to show their mother's name to be anything other than Elizabeth Robson. And that John and Elizabeth were both born in England, Bellingham area i presume..
The John Douglas born 1848 marries a Margaret Milburn by 1869 back in England in HArbottle and shows up as a Shepperd in Rothbury by 1871