McLanachan (34), an apprentice amenity horticulturist, lined up at the start near Clydevale against a backdrop of snow-capped hills and sleety showers, with a harsh wind chill.
''Once you got moving you warmed up pretty quickly,'' he quipped at the finish.
''It really helped, being a tail wind, as well.''
McLanachan was surprised at the ease and speed of his victory in 1hr 9min 4sec, as he has had to modify his approach to running due to his work and study commitments.
''You could say I'm running with more consistency now,'' he said.
''I'm actually turning up at races feeling very enthusiastic.''
This enthusiasm shone through when he won the Otago Peninsula Challenge two months ago, wiping 3min from his previous best time on the course.
He then eased his way around the half marathon course at the Christchurch Marathon event earlier this month in 1hr 12min 20sec to finish 20th in a high-class field.
To go almost 4min quicker in yesterday's event took him by surprise.
Romain Mirosa, who finished second, set off at an enthusiastic pace which spurred McLanachan into action earlier than he expected.
The two ran through the first 1500m together until McLanachan began to pull away and gradually extended his lead to finish 3min clear of second-placed Mirosa (1hr 12min 5sec). Simon Richardson was third in 1hr 14min 58sec.
McLanachan, who won the 100th running of the Edmond Cup Steeplechase in 2007, plans to give one of the country's oldest cross-country events another crack next Saturday. Based on current form, he will be among the early favourites to lift the senior men's title once again.
Another to back up a Peninsula Challenge title was Louisa Andrew, who won the women's title yesterday in 1hr 19min 34sec, holding out a strong challenge from Otago marathon champion Mel Aitken, who finished second in 1hr 22min 37sec.
Junior champion from the Christchurch event at Queen's Birthday Weekend, Emma Lloyd, was third in 1hr 28min 11sec.
Last year's open men's champion on the half marathon course, Jason Palmer, won the associated 10km event yesterday in 36min 12sec, in a hard-fought battle with 2012 Barnes Cross-country champion Allan Staite, who finished second in 36min 27sec. Alan Funnell was third in 37min 5sec.
First across the line in the open women's section was Megan Balchin (44min 46sec) from Jude Patterson (45min 53sec) and Dalise Sanderson (49min 46sec).
First in the 10km walk was Janeece Park, in 1hr 17min 26sec.
