The Monkey Towners defeated Subiaco Floreat by 79 runs in Sunday’s colts grand final at Breckler Park.
Keaton Critchell top-scored with 56 as Midland-Guildford made 207 before bowling out Subi for 128.
Noah Le Tessier was outstanding with 3-30, while Tom Gosling took 2-22.
On Saturday, Midland-Guildford claimed the first grade wooden spoon after a disappointing loss to Rockingham-Mandurah at Lark Hill.
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READ NOWA dominant Mariners partnership was the undoing of the Monkey Towners, who slumped to their fourth last-placed finish in eight years.
Ashley Mucciarone was best of the Monkey Towners bowlers with three wickets as the home side amassed 6-394 in response to Midland-Guildford’s first day score of 260.
The Mariners leapfrogged the visitors, with an unassailable seven-point lead separating the sides.