A grandmother who is the oldest woman to complete a North Pole marathon is taking on another challenge – an endurance race across the Namibian desert.

It is the third time Kenwynne Barber, from Epsom Close, West Malling, will run the 100km route, which takes in the world’s highest sand dune at 1,256 feet – four times taller than Big Ben.

As a retired security manager, the 76-year-old was used to chasing after villains, but she didn’t catch the running bug until she was 50, and marked the milestone by entering the London Marathon.

Since then she has done more than 100, racing in every continent in places such as Easter Island, the Antarctic, Disneyworld and the Inca Trail in Peru.

She is the oldest woman to complete the North Pole Marathon, which she did aged 66.

Mrs Barber said: “I just kept wanting to make them more and more difficult.

“I think a bit of insanity is involved, but it means I get to see the world.

“It is a lovely because there are no distractions. You are alone with your own thoughts.

“I have long chats with my late mother. It gives me time to think about my family and what they mean to me and I get that extra kick. I absolutely love it.”

When she takes on the challenge in December it will be the heat, not ice breaks and polar bears, that Mrs Barber will have to contend with – but she is confident she will make it to the finish line.

She said: “It’s amazing because you run past zebras and giraffes but last time I did it, it reached 57 degrees so keeping cool is a problem.

“I am terrified of heights so I have to go up the biggest dune with my eyes shut.

“As you get older if you don’t use it, you lose it, and I think it is keeping me mentally alert too. I’ve got arthritis and no illusions of winning it. I will plod my way to the end and it will take all day, but I will finish.”

This time Mrs Barber will be running for Macmillan Cancer Support, after her daughter’s successful fight against the disease.

So far she has raised more than £1,100. Donate by clicking here.