EXPLORER Robert Swan had to spend Christmas Day apart from his son – after he was forced to abandon a unique expedition to the South Pole.

The 61-year-old, who grew up near Barnard Castle, County Durham, teamed up with his 23-year-old son for the zero carbon South Pole Energy Challenge.

But half way into the epic 600 mile journey from their base on Union Glacier, Antarctica, Robert realised he could no longer meet the physical challenge.

Son Barney is continuing the expedition, the first to be powered solely by clean energy technologies and the 60 day trek is designed to prove they are able to operate in the world's harshest environment.

Robert, the first man to walk unaided to both north and south poles in the 1980s, took the decision during a two day camp half way to the South Geographic Pole having endured extreme winds and freezing temperatures.

He said: "We've had to make a very important...and right decision. And that decision is, that I Robert Swan, will not continue.

"The reason is very simple. So far we've been averaging eight or nine miles a day. I can manage that, just.

"But the team, in order to meet the deadlines to get to the South Pole, going up to the 14 miles a day. I'm just not physically capable of doing that.

Robert, who attended Aysgarth School at Newton-le-Willows, near Bedale and Durham University, remains in good health.

He was part of a team including expedition leader Martin Barnett and documentary filmmaker Kyle O'Donoghue, using man-hauled sleds to carry all the equipment needed to survive.

Robert added: "My son is continuing. I'm leaving Barney in the hands of two of the most capable people I know on earth. I'm extremely proud of Barney and I love all three of them."

This was to be his final major expedition.

Robert, who now lives in California but grew up in Whorlton and Wycliffe, near Barnard Castle, founded the 2041 Foundation, dedicated to the preservation of Antarctica.

An expedition spokesman said Robert had returned to the Union Glacier base camp to allow the team to move at a faster pace and to reach their goal before the season closes and conditions deteriorate further.

In a Christmas Day message, Barney said they had covered 11.5 nautical miles before pitching camp. "We are getting ready to wake up tomorrow morning and get on with our march."

Earlier, he spoke of the "poignant" moment his dad flew back to base.

"It was not an easy day to saying goodbye to dad. It was a bit sad to see him fly off."

The team are supported by some of the world's most technological companies, including NASA and Shell.

Today, the team have a further 223 miles to reach the South Pole.

For details visit www.2014.com or to follow their journey visit facebook.com./Shell