One of the world's last "great explorers", Sir Ranulph Fiennes, is attempting to become the first person to walk solo and unsupported to the North Pole.

The Old Etonian also hopes to raise £1m for the Cancer Research Campaign through sponsorship.

The 56-year-old adventurer, from Exmoor on the Devon-Somerset border, is heading for his base camp on Ward Hunt Island in the far north of Canada.

He will acclimatise for about a week before setting off on 14 February - St Valentine's Day - on the 700-mile trek.

Race is on

Sir Ranulph is planning to follow a "direct route" to the geographical North Pole, which he hopes to reach in the first week of May.

Hot on his heels will come another Briton, Londoner Alain Bywaters, who is planning to set out in March to conquer the North Pole alone with the Polex 2000 expedition.

Mr Bywaters, a 24-year-old former soldier, is taking a computer with him and plans to keep in touch with the rest of the world with regular e-mails.

The former SAS man has to carry a 500lb pack, stocked with enough food for 115 days.

Temperatures at the Pole often plunge to as low as minus 56 degrees Celsius.

As he left the UK, Sir Ranulph said: "It's great fun planning these expeditions and it's great when you come back.

"But to say the actual doing of it is enjoyable would probably be dishonest."

During a previous attempt to reach the North Pole in 1990 his frost-bitten toe turned gangrenous and part of the rotting flesh came away in his sock.

Sir Ranulph is an experienced explorer. In the 1960s he became one of the first Europeans to ascend the river Nile.

In 1982 he was one of the first people to circumnavigate the globe north to south.

'25% success rate'

In 1991, after 26 years of trying, he found the lost city of Ubar in Saudi Arabia, which Lawrence of Arabia called the Atlantis of the Sands.

Two years later he made the first unsupported crossing of Antarctica, with Mike Stroud.

Between expeditions he has written several books.

He told the Independent on Sunday: "It was never my ambition to be an explorer. From a very early age I wanted to be a colonel of the Royal Scots Greys to follow my father.

"I worked on a short Army contract for eight years but when I didn't rise above captain I decided to become an explorer."