McGlashan won all four singles against Eastern Harbour to effectively end the contest early, while St Clair had to go to a third-set tiebreak in the doubles to take its narrow win against Balmacewen.
The McGlashan team could be excused for some physical and mental fatigue after five hard ties during the week at the national Secondary Schools' finals in Auckland, with three of its players having 10 matches in three days. This followed five ties in an earlier week when the side won the South Island title in Timaru.
Paddy Ou claimed to be very tired from his workload, but had enough to hold out Aaron Hicks 6-4, 7-5 in the top single. By contrast Hicks was underdone, with few hard matches in the latter part of the season.
Harbour's Ryan Eggers worked his subtle variations to take a set off Carlos Reid, but Reid had superior power and found his targets to take the next two 6-0, 6-3.
Oliver Reid, a former student at the school, and Mitchell Sizemore claimed the same 6-3, 6-4 scores against Mike Smith and Chris Duncan and the title was won by mid-afternoon.
To both teams' credit, the doubles were played with intensity, and Hicks and Duncan scraped a 4-6, 6-3, 10-8 win over Ou and Sizemore, while Smith and Eggers beat the Reid brothers 6-4, 7-5.
St Clair women looked in trouble after Jessie Stevenson easily accounted for Nelson student Georgia Rooney for the loss of only one game, but Debby Stevens battled to a 6-3, 7-5 win against South Canterbury student Annabelle Ecroyd.
The doubles was all-important and St Clair fell behind by a set but the Otago Open titleholders Stevens and Rooney won the second 6-3 and, with the whole season coming down to a match tiebreak, dominated it 10-3.
