Some 250 children took part in sports at Roade School, near Northampton, as Dame Kelly met students and took part in activities including a relay.

Her visit was part of National School Sport Week, which aims to engage three million young UK people in sport.

Dame Kelly said: "I want to celebrate the work that goes on in PE and sport in schools.

"There are the health benefits, plus for a young person sport helps their confidence, gives them leadership skills and teaches them about teamwork. At Roade they have sport leaders and what you see from them is an added confidence which oozes from them.

"I think having the Olympics coming to Great Britain is probably one of the things that has helped with the project.

"Having top athletes going into schools does encourage a generation not only to be world-class athletes but to give it a go, because if they have a goal it doesn't matter what they do in life."

Children took part in a variety of sports, including climbing, tag rugby and swimming. Pupils joined the event from seven primary schools in the area.

Dame Kelly joined a team of Year Three pupils from Hackleton Primary School for a relay race.

One of her team-mates, Gaby, eight, said: "It was really exciting. We didn't know she was going to be in our team. She helped us do well."

Another team member, Emma, said: "She told us to keep cheering for our team mates and we could hear her cheering us on while we were running. It was really exciting."

Roade head teacher Ross Parkinson said: "I'm proud that we have been able to make a day happen through the work of our staff and young leaders and, in particular, make sure that children have been able to sample things they wouldn't normally try."