Maybe this is them in the 1861 census?
Reference: Class: RG 9; Piece: 3803; Folio: 5; Page: 4
(Private) East Street, Gateshead, County Durham
Shell, William Head M 60 Cooper b Northumberland
Shell, Mary Wife F 54 b Scotland
Shell, John Son M 21 Blacksmith b Northumberland
Shell, Tomas Son M 21 Sand Moulder b Northumberland
Shell, WIlliam Son M 20 Sand Moulder b Northumberland
Shell, Jane Daughter F 14 Scholar b Northumberland
Millen, James Michael Son-in-Law M 23 Tailor b Northumberland
Millen, Mary Daughter F 24 b Northumberland
Millen, William Leslie Grandson M 7 months b Gateshead
The same family in 1851:
Reference: Class: HO107; Piece: 2402; Folio: 320; Page: 38
Gateshead
Shell, William Head M 50 Journeyman Cooper b Wooler, Northumberland
Shell, Mary Wife F 47 b Berwick-Upon-Tweed
Shell, Mary Daughter F 14 b Newcastle Upon Tyne
Shell, John Son M 11 On Trial as a Blacksmith b Newcastle
Shell, Thomas Son M 11 On Trial as a Blacksmith b Newcastle
Shell, William Son M 10 Scholar b Newcastle
Shell, Jessie Daughter F 8 Scholar b Newcastle
Shell, Jane Daughter F 6 Scholar b Newcastle