Lloyd Scott spends the nights in a mobile home

He said: "I'm really looking forward to... when I get down The Mall and cross the finishing line, not just for myself but also for all the people that have helped me along the course."

On Thursday Mr Scott faced the most difficult part of the course - crossing the cobbles outside the Tower of London.

He said: "The first couple of hours this morning were the worst I have experienced. It was the first time that I thought I wouldn't make the finish in time.

"However, I never actually thought about stopping, there are too many people relying on me and I've already collected so much money."

'Stupid' idea

Since he started the 26.2 mile race the 40-year-old, from Rainham in Essex, has covered a little more than four-and-a-half miles each day.

I think it gives people some hope that they can go out and do things like this

Carole Scott

Mr Scott has modified the �2,500 1940s suit by removing the glass mask - so he can breathe - and making slits to allow him to go to the toilet.

He wears it for 12 hours at a time, with nights spent sleeping in a mobile home driven by supporters to look forward to.

Mr Scott's wife Carole, who has been following his progress with twin sons Luke and Elliot, eight, and daughter Aimee, 13, said the idea was "stupid".

But she added: "Knowing him like I do, I wasn't surprised when he decided to carry on and go through with it."

"I am really, really proud of him. I think it gives people some hope that they can go out and do things like this."

Mount Everest marathon

Mr Scott was diagnosed with leukaemia in 1987 and ran his first marathon two years later - to get fit for a bone marrow transplant.

He completed the course in three hours and 11 minutes.

Since his recovery Mr Scott has helped raise around �1m for CLIC - Cancer and Leukaemia in Childhood.

He has previously completed the Mount Everest marathon, ran across Death Valley, walked across the Sahara, climbed Mount Kilimanjaro in Tanzania and Mount Aconcagua in Argentina.