Little Oakley started impressively and took the lead when central defender Lewis Wood came forward to join the attack and net.
Rob Pratt had stepped in to lead the Harwich attack and he used his experience to help the young Shrimpers to become an attacking force when it seemed that the Acorns might take control.
Harry Hosking netted an equaliser for the Shrimpers and then the tables were turned when Ryan Pryke put them in front.
Little Oakley suffered a setback when Acorns legend Wood, who recently made his 700th appearance for the club at first-team level, was uncharacteristically red-carded.
From the free-kick that followed, Alex Pryke shot Harwich into a 3-1 interval lead.
In the second half, the young Acorns did well to overcome their numerical disadvantage and force Shrimpers goalkeeper Jack Lines to pull off some good saves.

First team beaten in season finale

Harwich also continued to perform well with neatly constructed attacks from which they came close to increasing their lead.
Although there were no goals in this half, there was plenty for the good crowd who attended to enjoy, with Luke Harrison and Martyn Rhodes' side celebrating their victory at the final whistle.
Harwich team: Jack Lines, Alex Pryke, Theo Stevenson-Miller, Jeremiah Ajisafe, Rory Breen, Tobi Dehinsilu, Aiden James, Hayy Kabangu, Josh Beavis, Harry Hosking and Rob Pratt. Substitutes: Ryan Pryke and Jinghan Qi (both used).