Teacher Audrey Schoeman collapsed while out walking in the Spanish Pyrenees last month and developed hypothermia before going into cardiac arrest.

Mrs Schoeman, 53, who lives in Spain but has a British passport, started “talking nonsense” as her eyes rolled back into her head and she stopped breathing, her husband Rohan said.

He added: “I thought she was dead.

“I was trying to feel a pulse… I couldn’t feel a breath, I couldn’t feel a heartbeat.”

Mrs Schoeman was airlifted to hospital, where her temperature was recorded as 18C (64.4F) – less than half what it should have been. Doctors could also not find any vital signs.

Medics at the Vall d’Hebron Hospital in Barcelona said Mrs Schoeman had suffered the longest cardiac arrest ever recorded in Spain, calling it an “exceptional case”.

Dr Eduard Argudo said: “She looked as though she was dead, but we knew that, in the context of hypothermia, Audrey had a chance of surviving.”

Hypothermia, although causing her body to shut down, also meant her brain and organs had been protected.

Dr Argudo added: “If she had been in cardiac arrest for this long at a normal body temperature, she would be dead.”

In hospital, she was put on a machine that removed her blood, re-oxygenated it, and then pumped it back into her body.

Then, once her body temperature had reached 30C (86F), she was switched to a defibrillator. It was then that her heart began working again, six hours after emergency services were called.

Speaking to local media, she said: “It’s like a miracle except that it’s all because of the doctors.

“Probably this winter, I won’t go to the mountains, but I hope that in spring we’ll be able to start hiking again. I don’t want this to take away that hobby.”

Mrs Schoeman was discharged from hospital 12 days after being admitted.