It was a routine heart operation which was all going smoothly until one thing led to another and the surgeon set fire to his patient.

The alarming but entertaining story of how a patient was flambéed on the operating table was told at Cheltenham literature festival by the leading heart surgeon and Guardian crossword setter, Samer Nashef.

Nashef, a cardiac surgeon at Royal Papworth hospital in Cambridge, said the operation had been a perfectly straightforward coronary bypass and they were just about to close the patient’s chest when the aorta dissected.

That is “one of the worst things; it basically transforms a straight operation into a very long and dangerous and tedious one”.

Because you cannot put the patient on the heart-lung machine, you need quick access to another artery, said Nashef. The groin is the best place but you have to prepare and clean the area.

“In a hurry, with an assistant pushing really, really hard on the aorta to reduce the massive blood loss, we threw some prep solution on to the groin and then cut the skin to find the artery.”

As there was some blood, Nashef used an electric device to cauterise it – a medical technique which involves burning to mitigate bleeding.

“Unfortunately the prep solution hadn’t dried. The flames reached the operating light. We managed to put them out using the drapes,”he said.

“To cut a long story short, the patient did absolutely fine but, he was an 80-year-old man, he was rather bemused to find he’d had a full Brazilian.”

The surgeon said he was congratulating himself on an amazing save but was nevertheless summoned to management and told what had happened was an NHS “never event”. Never events, such as taking out the wrong kidney, are – as the name suggests – events that should never happen.

The never event in this case referred to not burning or scalding patients, although Nashef argued the rule did not apply because the guidelines say it applies to kettles. There was no kettle involved in his operating room, he insisted.

Nashef, better known to Guardian crossword solvers as Philistine, was talking about his book, The Angina Monologues, sharing a stage at Cheltenham with fellow cardiac surgeon Stephen Westaby, author of The Knife’s Edge.

The discussion touched on how far along the psychopathic spectrum, how fearless and inhibited, surgeons should be.

Nashef said the quality was more important in surgeons practising in the early days of heart surgery when it was only carried out as a last resort. “The surgeons who took the chance to do that had to have supreme self-confidence in themselves.

“Now, we do not need to be so psychopathic. A good heart operation now should be as boring as possible, where nothing unexpected happens, where everything goes according to plan.”

The session was interrupted for five minutes when a man in the audience appeared to faint, even before Nashef’s fire-fighting story. Fortunately there were doctors – or rather surgeons – in the house, both of whom went down from the stage and diagnosed him as fine.