What seemed to be a quiet night on the road quickly turned into a heart-stopping moment for 38-year-old Vernon Lim.

The then SMRT taxi driver was travelling near the junction of Punggol Field and Punggol Road around 10pm when he saw a car parked on the right lane of Punggol Field road.

As he drove past, he stole a glance at the champagne-coloured Toyota and saw a man slumped over the steering wheel.

He quickly dropped his passenger off and made a U-turn to find out what happened.

Thinking that the man might have had a heart attack, he was trying to recall the steps to resuscitate him as he drove back.

When he approached the car, he found a nine-year-old boy in the passenger seat trying to rouse the unconscious man.

The boy lowered the window and asked for Mr Lim to help his father, Mr Alan Goh.

"I asked him to call his mum and, in the meantime, I called for an ambulance," said Mr Lim, after noting that the man was still breathing.

"The thing that worried me was that he was not responding," said Mr Lim. "He was in a car, so I didn't dare to move him."

The ambulance came in less than seven minutes, he said.

Mr Lim waited at the site for Mr Goh's wife, Madam Wendy Koo, to explain to her what had happened. He then drove her to Khoo Teck Puat Hospital where her husband was taken to.

Madam Koo offered to pay him the cab fare to the hospital, but he turned it down.

"I told her: ' I never had the intention to take money from you'," said Mr Lim. "Use the money to go and treat your husband and your son to a nice meal afterwards."

Recounting this incident, which happened in June, in a letter to The Straits Times' Forum page, Mr Goh could not thank Mr Lim enough.

The 44-year-old sales and marketing manager said he had a seizure that night, causing him to lose consciousness while driving his son home from a sporting event.

"I just blacked out and couldn't recall anything," he said. "My last memory was that I was driving out of the KPE (Kallang-Paya Lebar Expressway) tunnel."

Mr Goh managed to continue driving some distance before passing out at the traffic junction.

This is not the first time he has had a seizure. While it does not happen often, it was the first time he had one outside his home.

Looking back, he considers himself extremely lucky. "If someone discovered us much later, my life could have been in danger," he said.

Having plied the roads for around two years, Mr Lim said that he behaved just as any other driver on the road would have.

"To me, they've shown more than enough thanks," said Mr Lim, who is now a limousine driver.