Hi Gladys have not found any of the Blackhall family on the 1871 census, searched for them all individually but not luck, maybe they had gone back to Scotland? On the 1881 census I found the following;
George Blackhall age 63 born Scotland sawyer
alice wife age 62 born Scotland
John son age 28 ------------------ Tailor
ane daughter age 22 born Morpeth Teacher
William Foster Lodger age 25 born Shields Sawyer
address Darn Side Morpeth
Alexander Blackhall age 40 born Newcastle Timber Agent
Isabella wife age 35 born Ulgham Morpeth
Alice daughter age 20 born Morpeth
George son 18 born Morpeth Moulder(iron)
John son age 16 ----------------fitter(iron)
Alexander son age 14 ---------Pattern Makes(iron)
Elizabeth J. Blackhall dau age 12 born Hescot Northumberland
address Whale Bone Yard Morpeth
Robert Blackhall age 30 born Scortland Shoemaker
Catherine wife age 32 born Morpeth
Martha dau age 10 born Morpeth scholar
George son age 8 ----------------------------
Alice dau age 5 ----------------------------------
Robert son age ----------------------
address Darn side Morpeth
1891 Census;
George Blackhall age 73 born Scotland Wood cutter
Alice wife age 72
John son age 39Tailor
George Grandson age 12 born Morpeth
address Union Street Morpeth
Will Look for others on 1891 census later as I have Lunch to cook
Sheila