The historic trail has been divided into 50 one-day circular walks between seven and 19 miles long for the "Walk The Way In A Day" celebrations.

It is hoped the entire 268-mile route, from Edale in the Peak District to Kirk Yetholm in Scotland, will be completed.

The trail was launched on April 24 1965 when 2,000 people met on Malham Moor in the Yorkshire Dales on its completion.

Writer and rambler Tom Stephenson first raised the idea of a long green trail in 1935 but it took another 30 years for it to become a reality.

This is now regarded as the ultimate long-distance walking challenge in England Pam Warhurst, Countryside Agency

The Pennine Way is the oldest national trail in England and is used by 150,000 people a year on day trips and longer walks, with 3,500 people a year completing it from start to finish.

Pam Warhurst, deputy chair of the Countryside Agency, said: "This was our first national trail and is now regarded as the ultimate long-distance walking challenge in England.

"The high numbers of visitors are a testament to the good management of the trail and the finest landscapes it crosses."

Steve Westwood, national trail officer, said: "I don't think that there is a more fitting way to celebrate the 40th birthday of the Pennine Way than for walkers to visit every section of it.

"Hopefully for those who have not experienced the Pennine Way before, they will see what it has to offer and will then want to go on and plan walking the whole route in the future."