CHARLIE Strutton scored a last-minute winner to earn Chalfont the derby spoils at Holmer Green.
The striker headed in a priceless winner for Danny Edwards' side to capitalise on second-placed Tring drawing at home to Haringey Borough.
It means the Saints are now seven points clear at the Spartan South Mids Premier Division summit and with a game in hand.
Chalfont dominated the first-half but fell behind on 34 minutes when Eliot Derby put the Greens ahead against the run of play.
But the Saints rallied after the break with Strutton slotting away a penalty to level the scores and the influential striker netting the winner at the death and to take his goals tally to 22 for the season.
Defeat for Holmer was their third in a row and keeps them down in 18 th in the table.