Memorabilia from his days as a uniformed officer still dot his current office: a mug with the crest of the Singapore Prison Service, a framed message on the wall addressed to "Supt Lim Chong Teng".

In his 35 years of dedicated civil service, the former superintendent had at one point commanded over 200 officers, overseeing more than 2,000 inmates at Changi Prison.

Today, Mr Lim takes command at a different job, serving with security firm Soverus as a site operations manager at the CPF Building in Robinson Road.

"It was the easiest switch to make. With my experience and background, I did not have to go for additional courses or training," he said.

As superintendent, he earned close to $9,000 a month, almost three times what he earns now.

But the 67-year-old is content.

"At my age, I don't think I can get that sort of pay any more," he said. "Even if there is a higher paying job... I'd probably still stay with this one. It has its own challenges."

Mr Lim reports for work at 7.30am, five days a week, and goes home only at 6pm.

He busies himself with the deployment of guards, guiding his men, and monitoring a wall of screens that feed him live footage from cameras in buildings around the island.

Before his current job, he had worked briefly at the Ministry of Home Affairs, and then at another security company.

Even with two working daughters in their 30s, the idea of retirement is still far from his mind.

"I once met a client here. When he saw me, he said his father had retired at 55, and aged a lot within two years.

"When you don't work, you grow old faster," he said.