The challenge: a 2-mile swim in the Serpentine in Hyde Park followed by a 450-mile cycle from Marble Arch to Edinburgh over four days just in time for a 26.2 mile run in the Edinburgh Marathon. All back to back. And home in time for tea and cakes.

Sounds painful? It will be.

On 20 May this year I am doing this gruelling event in memory of my twin brother Jeremy who sadly died less than two years ago, and to raise funds for the charity set up in his name.

Jeremy died of new variant Creutzfeldt-Jakob Disease (vCJD), the human form of BSE. He was extremely unlucky. To date, less than 200 people are known to have contracted vCJD worldwide. He was reduced from the incredibly active, outgoing and successful person he was to a state in which he lost his ability to walk, remember, eat, co-ordinate, speak and do those things that we all take for granted.

Jeremy was a great adventurer and athlete and would certainly have loved to join me on this challenge (though would certainly moan less and get there faster). His approach was always to live life to the full. He achieved more in his short 30 years than most would expect to do in a whole lifetime, and inspired and encouraged others to achieve things they did not think they were able to do. It is in this spirit that I am doing this.

I am raising funds for his charity, the Jeremy Willson Charitable Trust, which my family and I set up shortly after he died. The charity helps fund people and projects that reflect my brother’s passions in life: helping young and disabled athletes and explorers, conserving mountain and ocean environments, and ground-breaking expeditions to remote areas of the world. You can find out more at www.jwct.org.uk.

I appreciate that there are so many worthwhile charities out there and there's only so much you can give but if you're inspired by what I'm doing please contribute what you can.

Matt