When Mr Redhza Abdul Rahim saw the President wearing batik, he realised he had made a big mistake.

The aide-de-camp (ADC), who was supposed to ensure that presidential events ran smoothly, had informed the President's guests at the Istana that the dress code required them to be in lounge suits.

But he had asked Mr S R Nathan to wear batik instead, resulting in the faux pas. "He looked at me and his face turned a bit red. Of course he wasn't happy, but he didn't say anything," Mr Redhza said of the incident that took place when he was a full-time ADC to the President from 1999 to 2001.

The next morning, when Mr Nathan called Mr Redhza into his office, he expected a tongue-lashing, as it was not his first day on the job and he had no excuse for his error.

But all that the President did was to speak to him calmly about the importance of checking and double- checking the smallest details.

For Mr Redhza, who was an assistant superintendent of police during the posting, that incident typified Mr Nathan, the boss: He was exacting and expected excellence from his staff, but it was not his style to turn to rebuke when they fell short.

Instead, Mr Nathan preferred to lead by example.

For his own swearing-in ceremony in September 1999, he personally went through every detail, from the seating arrangements, down to the minute-by-minute programme flow, to make sure the event ran smoothly.

This inspired respect from his staff, who were spurred on to do better so as to not disappoint him, said Mr Redhza, 47.

Despite his position, Mr Nathan had no airs.

Before their first meeting in the President's office, Mr Redhza was feeling nervous. But his anxiety dissipated when he saw Mr Nathan stroll in wearing a short-sleeved white shirt.

"I expected him to be in a suit, all businesslike, but he was very disarming when he spoke.

"There was just something in his demeanour that made people feel comfortable," Mr Redhza said.

Mr Nathan was also someone who truly cared about the welfare of his staff, and organised gatherings for those who worked at the Istana every few months so that they could let their hair down.

At these gatherings, he and Mrs Nathan made the effort to chat with everyone and took photos with every staff member who wanted a picture with the President.

"He made time for everybody, from the butlers, to the cooks, to the drivers," said Mr Redhza, who retired from the police force as a superintendent in 2014 and now runs a business that helps companies source for manpower.

When he received gifts of food, such as special fruit from overseas, Mr Nathan never kept them, preferring to distribute those items to the staff. He also made sure to set the right tone from the top when it came to work and matters of propriety, Mr Redhza said.

For instance, Mr Nathan made clear that he did not want special treatment, and expected the same of his staff. During a family holiday at a beach resort in Phuket, he reminded Mr Redhza to get the bill quickly so that he could pay out of his own pocket. He did not want the resort to pick up the tab just because he was Singapore's head of state, said Mr Redhza.

"He wanted us to be committed and devoted to the job. And it was easy for us to do so because we saw that he was a president who was devoted and committed to his office. So everything fell into place."