The teams gamely played out the match in stormy conditions, losing only ten overs to rain.
The Green batted first and scored 259 for the loss of only 4 wickets from their allotted 35 overs. Hemmings led from the front, opening the innings and scoring at a rate of a run a ball.
He received good support from Jack Stemp (39), Arnov Mahli (18) and Ben Purchese (55 not out) but with two overs to go he was still eleven runs short of the magic three figures.
Five were accrued from the penultimate over before it all came down to the final ball with two still needed. Hemmings firmly pushed the last delivery through the covers, and with his partner Purchese running hard, made it to his century.
In reply Ham & Petersham got off to a quick start, with a first wicket stand of 107 between Charles Reddish (35) and Fahim Ahmed (85). Both openers were then removed by Sid Iyer (3-42) as Pinkneys began to check the away team's romp to their target.
21 runs were needed off the last three overs with 4 wickets in hand. A parsimonious over from Freddie Avery and wicket from Mahli meant the men from Surrey still required 14 off the final six balls. Disciplined bowling from Avery and determined fielding from his teammates meant the result went Pinkneys way by a margin of 11 runs.
Centurion Hemmings (pictured) then made sure his team toasted their victory with a celebratory jug.
Pinkneys Green finish their season on Sunday with a home match against Fleet St. Strollers.