In the 1841 census for Hartfield village I found only these families named Slater:
HO107/1115/6/6 page 4 - Hartfield Village
John Slater, 55, Watchmaker
Sarah Slater, 50
Thomas Slater, 13
Jane Slater, 20
All born in county
HO107/1115/6/7 page 5 - Hartfield Village
John Slater, 80, Tailor
Jane Slater, 65
both born in county
HO107/1115/6/10 page 12 - Church Street
Fortunatus Slater, 75, Parish Clerk
Ann Slater, 85
both born in county
Could one set be John's grandparents? He may have been born at their home.
Also, the village smith is named John Winnifrith, 45, if it's any help.
Stovepipe