London - Detectives are baffled by the mysterious case of how a pensioner suddenly burst into flames on a quiet London street.

They have been unable to find anything at the scene that could have caused the sudden blaze that killed 70-year-old John Nolan.

In what appears like a case of spontaneous human combustion, the retired Irish builder caught fire in front of horrified passers-by close to Tottenham Hotspur’s White Hart Lane football ground.

Witnesses desperately tried to douse the flames before an air ambulance took the pensioner to Broomfield Hospital in Chelmsford, Essex.

He had suffered 65 per cent third-degree burns and died a day later after his devastated family agreed to switch off his life support machine.

Despite spending the last three months hunting for clues, police have been unable to establish what caused the fire just after 1pm on Sunday, September 17.

An investigation by the London Fire Brigade found there was no accelerant on the pensioner.

PC Damien Ait-Amer, the investigating officer on the case, said: "We have spoken with a number of witnesses who saw Mr Nolan ablaze, but we have yet to establish how the fire started."

"He was a well-liked member of the community and none of our enquiries so far have indicated that he had been involved in a dispute of any sort."

"Nor does any account given by witnesses suggest that he had been in contact with another person at the time of the fire." Mr Nolan followed his sister Mary to London in the 1960s and they were later joined by their other three siblings from County Mayo in the Irish Republic.

He had been living a few streets away from where he died in Haringey, north London.

Police said no arrests have been made in connection with the death. At the time, his family told an Irish newspaper of their heartbreak.

His brother-in-law, Tom Byrne, said: "John wouldn’t hurt so much as a butterfly. In fact he’d find a way to bring the butterfly home and care for it. He would do anything you asked of him."

He was described by neighbours in as a ‘gentleman’ and a ‘truly lovely man’.

Mr Nolan’s nephew, Kevin Byrne, told The Sun: "He suffered such burns that they said a younger man would struggle to survive the injuries, so an older man who was frail would never survive it."

"He had his organs burnt ... his face and head were swollen and his hair was burnt off, it was really horrible stuff." He added: "How does a man just go on fire in the middle of the street? My uncle had a stroke many years ago and he was vulnerable."

"He wasn’t working and he wasn’t even a great conversationalist, he was quiet and needed care." A post-mortem examination gave Mr Nolan’s cause of death as severe burns. An inquest into the tragedy will open at Barnet Coroner’s Court in March.

Police have asked that anyone who saw Mr Nolan on fire call PC Damien Ait-Amer on 101. They can also tweet information to the Metropolitan Police via @MetCC. 

There have been around 200 cases of spontaneous human combustion documented throughout history, with victims often elderly, sick, or under the influence of alcohol, which could explain why they are unable to escape the fire.

A coroner ruled the death of 76-year-old Michael Faherty in Galway, Ireland, in December 2010 was the result of spontaneous combustion. He decided the fireplace in the sitting room where Mr Faherty’s charred remains were found was not what caused his death.