The new online BBC Three will exclusively cover Eddie’s journey, from his first marathon on Tuesday 23 February to his last marathon planned for Sunday 20 March.

Eddie has chosen 27 marathons to reflect the 27 years that Nelson Mandela spent in prison. Throughout his journey he will explore the history of South Africa and Nelson Mandela as well as visiting communities, organisations and families that have all been helped by the work of Comic Relief.

The mammoth undertaking will culminate in Pretoria on Sunday 20 March, at the same time as the Sport Relief Games will be taking place across the UK.

Eddie’s route will trace the story of Nelson Mandela’s life, starting in his birthplace, before journeying to the school and university that he attended, then on to Cape Town and Robben Island where he was imprisoned. If Eddie completes all 27 marathons, he will end at the Union Buildings in Pretoria where Nelson Mandela gave his inaugural speech as the first democratically elected President of South Africa in 1994.

Izzard previously attempted a similar feat in South Africa in 2012, but had to pull out for health reasons. The 2012 attempt followed his fantastic effort for Sport Relief in 2009, when he completed 43 marathons in 51 days across the UK, pushing through both physical and emotional barriers to raise over £1.8m.

The money raised for Sport Relief from the Eddie Izzard: Marathon Man challenge will be used to help transform the lives of some of the most disadvantaged people both at home in the UK and across the world’s poorest communities.

Izzard says: "I was inspired to run 27 marathons in 27 days for Sport Relief after seeing the film Invictus. The film featured a poem called Invictus - one of Nelson Mandela's favourite poems during his 27 years in prison. He used it to give himself determination to keep himself going and keep his spirit alive. It's a beautiful poem about being the master of your own fate and destiny. Watching the film I suddenly realised - I have to run in South Africa. I should run 27 marathons in 27 days as a salute to the great man. It is also a salute to all who struggled and fought against Apartheid."

"ps.. I tried to do this four years ago and failed. This time I will succeed. But if I fail, I will come back again and again and again until I do succeed. Because that's what Nelson Mandela would have done."