Sir Ranulph has walked unaided across Antarctica

The 59-year-old record-breaking adventurer had a heart attack on board an easyJet plane which was due to take off from Bristol airport to Edinburgh on Saturday.

Cabin crew contacted emergency services and he was taken to the Bristol Royal Infirmary where he had surgery on Saturday night.

Sir Ranulph's wife Virginia is at his bedside.

A hospital spokeswoman said: "Sir Ranulph remains in a critical but stable condition. He is still in intensive care."

The bottom line is that you don't see a crevasse until you fall down it Sir Ranulph Fiennes

An easyJet spokeswoman said on Sunday that 130 passengers and five crew had been on board the flight, which was delayed for three hours.

Sir Ranulph's expeditions to remote parts of the globe have seen him achieve outstanding goals - and overcome potentially life-threatening situations in the process.

"The bottom line is that you don't see a crevasse until you fall down it," the old Etonian once said.

In 1993, Sir Ranulph became one of the first men to walk unaided across Antarctica.

Severe frostbite dramatically halted the Exmoor-based explorer's attempt to reach the North Pole in 2000.

He plunged into freezing water when one of the two food supply sledges he was towing fell through thin ice.