David, There were not too many people residing in Bolnhurst in 1750 - just enough to fill a page of A3 paper, & yes it has John Saby as you described but not a Joseph Sab(e)y or any other Sabeys; perhaps he was one of the 8 people recorded as living in his household; which wasn't his household as the landlord was John Lawson & the rent was £45.00 .
The inhabitants were grouped as follows ::-
Farmers
Robert Wyat, John Smith, George Freshwater, James Ashburner, William Goodley. John Saby. John Wells, John Church, Samuel Maxey, John Wadsworth, John Wadmore, Thomas Fendham
Cottagers
William Crafts, William Cunningham, Gyles Smith, Thomas Elms. William Fodery, John Peck, William Milton, John Northfield, Henry Saunders, Richard Keely, Robert Wakefield, William Braubrook, William Dawson, John Carter, Nenjamin Squire, Thomas Lewis, Robert Saunders, John Bennington, William Feary.
Eleemolyaries
Edward Jackson, Wid Berry, Wid Feary, Wid Beal, Eliz Crafts, John Stokes, Mary Hall, Mary Hemmington, Anne Hardwick.
Outdwellers
Owen Goodchild (Little Staughton), Joseph Marshall (Pertenhall), Franklin, esq (Gt Barford), James Fuller (Tillick), Henry Shadbolt (Keysoe), John Skinfield (Thurleigh)
Omitted
Thomas Spencer, Wid Wyatt, William Goodman, Thomas Horton.