The Lamb National was introduced by rangers at the farm in Thornhaugh, near Peterborough, as a way of making bottle-feeding more fun for the then, young lambs as they moved outside from the safety of the barn.

But months on and the bundles of wool – Milky, Monty, Jemima, Larry, Minty and Eric – who are now fully-grown sheep, can't get enough of running around the specially- designed S-shape course.

They scramble to complete the course, which includes three sets of hurdles made from bales of hay, to see who can tuck into the big bucket of feed at the finishing line first.

With their "jockeys" – cuddly toy ladybirds, frogs, bears, dogs and tortoises – strapped to their backs, the orphan sheep, who were given their names by visiting schoolchildren, lined up behind the starting gate and then chased one of the farm rangers, who had the bucket of grub, to the finish line.

Children stood in "ewe" of the sheep and placed a free bet on which duo would win the race.

Throughout Sunday's event, all eyes were on Minty and his jockey, the tortoise, as they did a little warm-up before sprinting off, leaping over the bales of hay straight to the finish – feet in front of all the others.

Ben Reed, from Market Harborough, was visiting the farm with his family when the lamb racing took place.

He said: "We have been camping at the farm over the weekend. it has been great fun, and the lamb racing was an extra treat for the kids. they loved it."

Deputy manager Vivienne Duffy said: "We started the lamb racing at Easter as a way of weaning our newborns off the milk, and as a bit of fun. But before we knew it, we had built a circuit.

"It is a great way to exercise the animals, and they really do enjoy it.

"As soon as people start crowding around the fence, they know it is time to race, and also know that they will get a reward at the end of it."

Farm ranger Kerry Hill said: "It is just a bit of fun. the children love it and, most importantly, the animals do, too."

You can see the woolly jumpers in action twice a day throughout the rest of the school holidays. In September, they will just race at the weekends.

For more information on what's happening down on the farm, visit www.sacrewell.org.uk or call 01780 782254.