Their 3-1 victory away to St Peter was sweet revenge following their 3-0 defeat by St Peter in the division’s President’s Trophy final last Thursday at Springfield.
Undefeated Grouville scored through Tom O’Toole, James Walsh and Jon-Joe Hill at St Peter with the hosts getting their consolation via Alex Haine.
Rozel Rovers will finish runners-up after they scored five times without reply at Le Couvent against St Clement. Mark Le Lievre hit a brace and Tommy Ling, Alex Gibb and Danny Huet one apiece.