A total of 11 amateur adventurers in four teams are now involved in the 400 mile trek to the Magnetic North Pole.

Mr Butler had trained by pulling tyres around an airfield, and was planning to take part in research into the treatment and prevention of diabetes during the expedition.

He said: "There were always two challenges.

'Valuable experience'

"The first was to raise the money and the second to walk to the North Pole.

"I would like to say a big thank you to all those who have supported me.

"I have gathered valuable experience and good advice which I am still keen to use."

The teams are due to set off from Resolute Bay in Canada on 9 April.