"Don't worry," he calls to a group of students stood applauding, their own dogs straining at their leashes. "I'm not going to ask you to pen the sheep."
The 11 students are in the third week of an evening course in sheepdog training in the fields of Hartpury College, Gloucestershire, a higher and further education college specialising in agriculture and horticulture.
During the six-week,pound;50 course, they will learn commands such as "come by" and "away to me", and how to perfect their whistling. Other topics include choosing a pup, shedding and penning and even making a shepherd's crook.
Dogs are required to be aged between 10 and 42 months, and must be able to stop on command.
The course is proving popular. There is already a waiting list, with enquiries from as far afield as Staffordshire, and students have travelled to Hartpury from throughout the West Country.
"After the One Man And His Dog television series, there was an awful lot of interest in sheepdog trialing and people started buying border collies," says Chris Lee, himself a former sheep farmer.
"People on this course are from all sorts of backgrounds. Most have access to sheep and to a dog and they want to train it.
"Our interest is to try to train good shepherding dogs. There's still a tremendous importance in sheepdogs and the way we use them. A lot of shepherds use all-terrain vehicles these days, but there are vast areas in Wales, Scotland and the Yorkshire Dales where it's impossible to keep sheep without working dogs," he says.
Sheila Hawes, from nearby Upleadon, enrolled on the course with Tonka, an Australian Shepherd dog. "I wanted to try him out for what he's bred to do," she says. "The course is very good so far, considering most of us are learning and the dogs are learning too."