This is the third year Leishman and his wife Jo have produced the series. It screened on TVNZ6 and then TVNZ7, but the closure of both those channels has led to Road to ... finding a new home on Heartland.
"We're delighted; it's a lovely fit - let's face it, there's nothing more 'heartland' than this," Leishman laughs.
"The idea is to give viewers the opportunity to get to know the Young Farmer contestants better, so by the time they get to the final they have a vested interest in who's going to win.".
Two-thirds of each half-hour episode are dedicated to a regional final in which contestants have to demonstrate "the wide variety of qualities you need to be top young farmer: general and farming knowledge, as well as practical nous - you have to be part vet, part builder, part mechanic..."
Although there are pre-requisites the competition events have to satisfy - a sheep module, for instance - the regional committees otherwise have free reign to decide the specific content of their area's contest. That can mean "the odd head into a plateful of trifle", laughs Leishman. "Tonight's episode is the Waikato/Bay Of Plenty final and it includes making a surfboard and then running through big concrete pipes while being hosed with water by the local fire brigade."
The final third of every instalment looks at the regional winner's "home life, their farm and how they run it, what their other interests are", which can result in some surprising insights. "For example, Ian Douglas, the guy who won the Northern Regional Final last week, has a background as a restaurant manager for Gordon Ramsay - who'd have figured?"
The series confounds many cliches regarding what's required to run a successful farm.
"These days it's a given you've got some sort of degree, and just about every contestant does have a tertiary qualification," Leishman notes. "As well as hands-on skills, you need to be a pretty darn good businessperson, because you're dealing with a very valuable asset."
The agricultural industry is also far from the male preserve it's been traditionally regarded as.
"This year six women entered the contest. That was unheard of when I got involved 13 years ago, because it just seemed a blokey thing to do. And they acquit themselves extremely well. Sometimes the men have a physical advantage, but most of it," says Leishman, tapping his head, "is about the top two inches."
Road to the Young Farmer Final screens Sundays at 8.30pm on Heartland.
