A retired nurse talked his trainees through saving his own life when he suffered heart failure during a CPR lecture.
David Knowles was delivering a first aid course to members of his Exeter church group when he started feeling unwell.
The 77-year-old said he felt dizzy and weak, and had to lie down.
He then instructed his trainees, who thought he was role playing, on what to do before he passed out.
"I had just started my lecture and we were talking about cardiopulmonary resuscitation," Mr Knowles said.
"The more senior members of the group had asked for a demonstration...she thought I was role playing, but I told her it was real and that I was going to lose consciousness."
'I woke up weeks later'
Mr Knowles, a St John Ambulance volunteer, went into cardiac arrest, but his trainees called 999 and gave him CPR until an ambulance crew arrived.
"I'm told I came to, briefly, and was talking to the paramedics about my condition, but the next thing I remember is waking up in hospital, two and a half weeks later," he said.
Mr Knowles was alone setting up his lecture in the church rooms on 16 February for between 10 and 20 minutes before his students arrived.
St John Ambulance said if he had gone into cardiac arrest during that period, with no-one on hand to revive him, he would almost certainly have died.
At the Royal Devon and Exeter Hospital, Mr Knowles suffered a further cardiac arrest and a pulmonary embolism.
He was hospitalised for five weeks, and left hospital in mid-March.
Doctors feared he might have suffered brain damage, that his internal organs could have been affected by his ordeal and predicted he would need months of rehabilitation.
But medics say he is making excellent progress, is mentally alert and can walk unaided as he continues to recover at home in Newtown, Exeter.