Mermaid have completed their charge up the Herts Ad Sunday League with a third title in three seasons.
They went into their final game of the year just needing to match Brookmans Park's result to pip them to top spot in Division One.
And they did it in style with a 4-0 success over Forever Young People.
Ben Taylor's looping volley put them on their way and he completed his hat-trick in the second period with a free-kick and a penalty.
Harry Crooks added the fourth.
They could make it a double success as they take on Six Bells in the final of the Goulding Senior Cup on Sunday.
Park also won on the last day, 1-0 against The Bull courtesy of a Sammy Kinsley strike, but it left them second on goal difference.
A 5-1 win for Strafford Arms over Plough & Harrow has all but given them the Premier Division title.
They now have a nine-point lead over Borehamwood Rovers and need just one more from their final game to clinch the crown.
Stephen Dodd, Scott Buddington, Jack Davis, Max Bradford and Erivaldo Felix got the goals with Tommy Biswell replying for Plough.
Phoenix Res moved closer to a third-placed finish in Division Thee with a thumping 10-0 victory over TNF.
They are one point behind Strafford Arms Res but have two games in hand.
Michael Langton scored three and there were doubles for Robert Calancea and Radu-Mihai Stefanoaica.
Jack Gage, Thomas Meritt and Liam Addlesee got the others.
In Division Four, Cub won 6-3 against Royston Rangers in a mid-table battle, Cameron Ferguson (two) and Ryan Lawler scoring for Rangers.
Borehamwood Rovers suffered the agony of defeat in the final of the Herts Sunday Senior Cup, going down 4-2 to St Josephs South Oxhey at the County Ground in Letchworth.
There were two cup finals in the league on Sunday too, both played at Clarence Park, and both needed a shoot-out to decide the victors.
Welwyn Warriors and Alban Dynamo had drawn 1-1 in the Intermediate Cup, Calum Paine on target for Welwyn, but it was Dynamo who raised the trophy, 4-3 on penalties.
Before that the Goulding Junior Cup between The Wrestlers and Saints had finished 0-0.
And it was the latter who triumphed this time, 5-4.
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