It was 40 years ago, but veteran banker Edwin Khoo remembers it quite clearly.

He was a teller at Citibank - known then as First National City Bank - and he found he was regularly processing cheques faster than his colleagues so customers kept hopping over to his queue.

"I went to my boss and said there has to be a better way. He said, 'You go think of one'," Mr Khoo recalls.

He did just that and suggested a common queue system, where customers in a single line are served by the next available teller. No more guessing which teller was faster, no more anxious queue-hopping.

The system was eventually adopted by other banks.

On another occasion, he found that cash boxes ran out all too soon during pay days, and customers had to wait in line longer. (In those days, it was common for workers to cash their pay cheques at banks.) He asked for more cash.

Simple solutions that resulted in vast improvements in customer service - these were demonstrated by Mr Khoo time and again as he rose through the ranks to become one of Singapore's best-known consumer bankers.

"Banking is not rocket science. You just have to know what your customer needs, when he needs it, and be there," he told The Straits Times in his final week at DBS Bank, which he joined from Citibank 10 years ago, before retirement.

"Every banker knows that. But not many practise it."

When heading the car loans department at Citibank, he pioneered balloon loans and other deferred payment schemes, as well as an "instant" electronic loan approval process based on a checklist of parameters.

When heading the small and medium-sized enterprises (SMEs) division at DBS, he got to know what each business person needed and made sure they had swift access to credit lines.

"You know a bak kua (roasted pork) business will need to buy stock from around September, because prices will skyrocket towards Chinese New Year," he said.

"So you make sure the credit line is ready by September."

He forged strong relationships with clients, sometimes going the extra mile to "show support".

"In business, it's all about relationships," he said, repeating a well-used line.

And he has results to show for it. Between 1985 and 2003, he grew Citibank's car loans portfolio from zero to US$1.2 billion.

When he headed DBS Bank's enterprise banking unit, which dealt with SMEs, between 2004 and 2011, the business grew its asset book threefold.

Businessman John Lou, 58, who is in palm oil, said: "He's street-smart, he thinks out of the box and he understands business right away."

Yet, "he knows who's taking advantage and who genuinely needs financing".

Porsche dealer Karsono Kwee remembers how Mr Khoo helped him in his early years.

"It was 1985, the market was very bad because of the Pan-El bust, and the previous Porsche importer had run away with customers' money."

As a result, no bank wanted to finance Porsche cars. "Edwin was the first to open the door," he said.

DBS Bank, which named Mr Khoo senior adviser after he handed the enterprise reins over to Mr Lim Chu Chong in 2011, has a glowing tribute for the veteran, too.

"During his time at DBS, Edwin took the bank's SME business in Singapore up many notches by being more customer-oriented and stepping up on marketing and service," said Ms Jeanette Wong, group executive of institutional banking group at DBS.

"He is a consummate marketer and especially strong with client relationships."

Mr Khoo, who turned 62 last Friday, will not be turning his back on corporate life completely though.

He is considering a couple of directorships and has set up a property broking venture in China.

"I will miss colleagues and clients most - but not the budget and business reviews," he said.

"I know my next phase is uncertain, but I am willing to try new things. I also look forward to spending more time with my family."