In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Elstob like this:
ELSTOB, a township in Great Stainton parish, Durham; on the Clarence railway, 8 miles WNW of Stockton-upon-Tees. Acres, 733. Real property, £449. Pop., 30. Houses, 6. The name is thought to be a corrup-tion of "Ella's stob, " derived from the fact that Ella the Dane, after landing, first pitched his tent here.
GB Historical GIS / University of Portsmouth, History of Elstob, in Darlington and County Durham | Map and description, A Vision of Britain through Time.
Date accessed: 26th April 2017
Click here for more detailed advice on finding places within A Vision of Britain through Time , and maybe some references to other places called " Elstob ".