2018–19 Spartan South Midlands Football League Division One

At the end of season 2017–18, the following teams left the division: The remaining 17 teams, together with the following, form Division One for 2018–19:
 * Promoted to Step 5
 * Baldock Town, to the Premier Division
 * Southall, to the Premier Division
 * Relegated to Step 7
 * St Neots Town Reserves
 * Promoted from Step 7
 * Amersham Town, from Division Two
 * Park View, from Division Two
 * Transferred within Step 6
 * Buckingham Town, from the United Counties League