An IT consultant will take part in “the toughest footrace on Earth” to raise money for two charities that helped his mother before she died.

David Gilmore, 34, has been training hard in Richmond Park for the biggest physical challenge of his life – running more than 150 miles over six days in the sweltering Sahara in Morocco.

Mr Gilmore, of Little Queens Road, Teddington, will need to carry all his own kit, including bedding, food and cooking equipment, in the Marathon des Sables in April.

He hopes to raise £8,000 for Macmillan Cancer Support and the St Wilfrid’s Hospice, in Eastbourne, which looked after his mother Nora after she fell ill with lung cancer. She died in 2008.

Mr Gilmore said: “It’s not the easiest time and they just made everyone’s life as tolerable and pleasant as it could be. At the hospice mum had a little Yorkshire terrier called Rocky and they allowed her to take him in. It’s just about as nice as you can get.”

Visitors to Richmond and Bushy parks will be able to spot Mr Gilmore running there ahead of the ultra-marathon, and he has also been hill training with his backpack, sprinting up and down some of the borough’s steepest gradients.

He said: “I’m not a natural athlete, I have to say. I did the London Marathon in 2004 but it wasn’t particularly fast, four-and-a-half hours, and I hated every minute of it. I swore never to do it again.”

He will have to run in temperatures at times exceeding 50C and on day four will cover the distance equivalent to back-to-back marathons.

He has already raised more than £3,500 but hoped the extreme lengths would encourage people to donate more.

He needed to pay £4,000 just to enter the ultra-marathon, which attracts runners from around the world.

To make a donation, visit uk.virginmoneygiving.com/DavidGilmore.