Kingstonian will face AFC Hornchurch for a place in the play-off final after Dan Sweeney’s goal in a 1-1 draw at Dulwich Hamlet secured second place on goal difference.
Relegated Carshalton Athletic went out of the league on a high thanks to a 2-0 win over Hampton & Richmond Borough.
Goals from Jason Henry and Sean O’Toole brought the Robins’ miserable season to an end at Colston Avenue.
The Beavers, who finished 12th in the table, could be mistaken for having next week’s Middlesex Senior Cup final on their mind.
Ahead of the first of two cup final appearances, Met Police went down 1-0 at AFC Hornchurch to end a disappointing domestic season in 17th.
Ryman Division One South
Jamie Coyle and Mohamed Eisa got the goals that guided Leatherhead to a 2-0 win over Worthing at Fetcham Grove.
Despite the three points, the Tanners dropped to third in the table and will host Guernsey tomorrow night [Tuesday] in the play-off semi-final.
Corinthian Casuals’ Jamie Byatt ended the season with 29 league goals after his double appropriately sealed a 7-0 demolition of Redill.
Joe Hicks, Ross Defoe, Mahrez Bettache, Saheed Sankoh and Ellis Wilson-Joseph were also on target, leaving the Casuals 17th in the table.
Louis Glace-Palmer grabbed the consolation, leaving the Swans one spot above the drop zone.
Walton Casuals endured a foul end to the season, going down 6-0 at Hythe Town, while Juan Onieva (two), Tinashe Nkoma and Sol Pinnock got the goals that saw Tooting & Mitcham United past Faversham 4-2.
Casuals finished the season in ninth, while the Terrors were 11th.
This week’s fixtures
Ryman Division One South play-off semi-final
Leatherhead v Guernsey
Ryman Premier play-off semi-final
Kingstonian v AFC Hornchurch
Surrey County Cup final
Met Police v Woking (at Woking)