Carshalton Athletic U15 whites added to their Surrey Cup glory earlier this season by winning the London Cup final on Sunday.
In a tight affair, the Robins eventually saw off Brimsdown Rovers 1-0 with the winning goal from Calum Phillip coming with just seconds of normal time remaining.
Coach Rob Scantlebury said: "Our form going into this game had been mixed, but the boys knew they would have to raise their game.
"They and their parents have done us proud and are a credit to Carshalton Athletic."
Carshalton were indebted to goalkeeper Sandile Manzi for denying Brimstone with a full stretch save on a deflected shot in the first-half, while goalscorer Phillip had just returned from a broken foot and only entered the fray with five minutes to go.
"They had the better of the opening 45 minutes but I was pleased with our response in the second-half," added Scantlebury.
"We turned the tide and kept them under pressure for long periods, with our goal being the reward.
"Some of these lads have been with Carshalton since aged eight and achievements like this prove that patience, commitment and a well-thought out youth development strategy can pay off."