Sport on TV: Not-so-fast Eddie sets a blistering pace in the Cape

Eddie Izzard may be a brilliant stand-up comedian but he would have required extra powers of fortitude to stay on his feet after his latest endurance test. Three years ago he ran 43 marathons in 43 days around the UK in aid of Sport Relief, despite having no pedigree at long-distance running. It was an astonishing undertaking, but no undertaker was required.

In Eddie Izzard's Mandela Marathons (Sky One, Thursday) he went to South Africa to run 27 marathons in as many days because "I want to say 'thank you for existing' to Nelson Mandela" and to pay tribute to the South African leader's 27 years in prison. Not as bad as before, you might think, now he is an old hand – or rather foot – but this time he is running in his socks and the road surfaces are covered in rocks. You can feel every last biscuit crumb under the sofa cushions as you watch him.

The 51-year-old Izzard comes across as a jolly decent sort and you don't want to see him suffer. It makes you want to shout at the telly: "Just put your shoes on, man!" Or, given that he has a penchant for cross-dressing: "Put your high heels on, at least." Perhaps years of strutting around in stilettos has hardened his sole.

One stretch of road near Mvezo, Mandela's birthplace, features a roadsign saying: "Danger: Bad Road. Remove dentures and hearing aids!" Izzard has obviously heeded the advice because he takes no notice of those who think he should slip on a comfy pair of sneakers.

Since his first milestone run in 2010 he has espoused the "barefoot technique" and at least he is following in the footsteps of the local population in that regard. But he only manages three marathons in the first of the two episodes, so he had a lot of catching up to do in the second instalment. In fact he had to abandon his first attempt after a mere four runs. It remains to be seen if he went back.

Unlike last time, this attempt seems like more of an excuse for a TV series and a DVD – although all proceeds went to South African charities. At least it means all the gruesome hobbling is alleviated by occasional footage of his stage act. But if the man is prepared to put himself through such agony to make a TV programme then you can hardly kick up a fuss.

At the same time he provides an illuminating history lesson about the great man's life. And anyway, as he says breathlessly, "It's healthy, no one's dying, which I think is the essence of what sport is all about". So he manages to wrap three elements up into one – if only he had done the same to his feet. He even gets to have a village-full of schoolchildren running after him in the manner of Muhammad Ali training in the streets of Kinshasa.

Hopefully someone brought his efforts to the attention of Mandela because it would be a shame to go all that way and not meet the man who made such a remarkable feat of running the country.

* Another man who used to run a fair bit, Linford Christie, was featured on RHS Chelsea Flower Show (BBC2, Tuesday), where he is apparently something of an habitué. But you had to wonder why he has been attending the event for 13 years when he showed pictures of his garden – there's just a patch of grass and a tree.

The former 100m champion said that when he was a boy his job was to pick caterpillars off his father's tomatoes and sweetcorn. Now that's life in the slow lane.

When Alan Titchmarsh asked about the similarities of sprinting and gardening in terms of discipline, he explained it's all about patience. "You've got to wait patiently for one leg to hit the ground, then the other one to come through." Just think how fast he would have been if he hadn't worried about all that and just ran his socks off.