The Asia-Pacific chairman of KPMG, Mr Tham Sai Choy, 57, was contemplative as he sat in a plush room on the 22nd floor of the firm's office in Raffles Quay.

He recalled an incident from his early days as a chartered accountant with KPMG - then known as Peat, Marwick, Mitchell & Co - when he had visited a Singapore office of an investment bank with a senior partner of the auditing firm.

Mr Tham remembered being impressed by the bank's aesthetically pleasing workspace, with its amenities and carpeted floor.

"Some day, we will have carpets in our office as well," he recalled saying to the senior partner - a remark reflecting the aspirations of a young man determined to see his company climb the ladder of success.

Today, KPMG is a globally renowned firm with a presence in 155 countries, and is recognised as one of the Big Four accounting, taxation and advisory firms in Singapore. Last week, it celebrated its 75th anniversary - a milestone for a firm which had a staff strength of just one in 1941, but was judged to be the largest accounting firm here last year, based on the total staff number of 2,900.

From being late entrants to the Singapore landscape, to briefly shutting shop during the Japanese invasion of World War II, to re-emerging and establishing itself as KPMG, the company has come a long way.

The success is a result of the dedication and hard work of many, one of them being Mr Tham, who has spent more than 30 years with the company. He joined the firm immediately after qualifying as a chartered accountant in the United Kingdom in 1984.

Besides learning the nuts and bolts of the profession, the UK experience had opened his eyes to how critical credibility is to the business of accountancy.

It was a lesson that would stay with him all his life. Take away credibility, "and all modern business grinds to a halt", he noted.

That lesson proved to be the most relevant one for Mr Tham as he embarked on a career in Singapore - a nation that put a premium on credibility on its journey to establishing itself as a global financial centre.

But that was not the only thing he learnt in Britain.

Mr Tham's university experience was equally rich, as his school allowed the young student to take up more courses than necessary, out of personal interest. Encouraged, Mr Tham made use of the opportunity to learn to use the computer, and got hooked. His enthusiasm for digital technology and innovation remains strong to this day.

Years later, when electronic mail made its appearance on the digital landscape, Mr Tham was among the first to realise its significance and decided to get onboard.

Fascinated by the numerous possibilities e-mail technology would bring, Mr Tham pitched the idea to his superiors and successfully persuaded them to implement it.

Once he got the go-ahead, he procured the necessary hardware and software and set up the entire system, only to realise there was no one to send an e-mail to - a conundrum he likened to how Alexander Graham Bell might have felt after inventing the telephone.

"So Thamsaichoy 1 sent an e-mail to Thamsaichoy 2," he said with a laugh about sending the first e-mail to himself. Today's smartphone- flaunting generation may find older people to be technology dinosaurs, "but it was my generation who made all this happen", said the 57-year-old father of three.

Six years after he joined the firm, Mr Tham was admitted to the partnership in KPMG.

Over the next two decades, he went on to serve it in various roles: heading the firm's audit practice in Singapore and the Asia-Pacific region.

At various other times, he played important leadership roles in work involving capital markets, restructurings and corporate governance.

Since 2013, he has served as chairman of KPMG in Asia-Pacific.

In all that time, Mr Tham encountered many more changes in the sector and has been in the forefront in guiding and steering the KPMG wheel to meet the challenges of the new world.

As business needs changed, KPMG evolved in its role - from being just an accounting and auditing firm, to playing a bigger part in an advisory role. "We are auditors, we are tax advisers, we are general business advisers," he said about the diversified portfolio of the company.

Another change was the advent of data, the byproduct of digitisation, as a central theme of modern businesses. "Even Formula One races depend on data," he pointed out.

Data can be used as intellectual property, but it also comes with risks which we understand as cyber security, he said.

New auditing rules to set in in December will also be a significant change to the status quo in the sector. Auditors will have to shed light on key audit matters encountered during the audit instead of just reporting whether a company has passed or failed the audit.

That requires auditing firms to be "more committed to stakeholders and more tuned to all their needs", Mr Tham said, stressing that KPMG is ready for the new responsibility.

Changing times have thrown another curve ball to the sector in the form of artificial intelligence. Many fear machines will replace humans at their jobs in future. But Mr Tham believes that while some jobs do require quality with timeliness, others need a human touch.

"Machines cannot completely replace people. People are at the heart of our business, and are still needed to transfer knowledge to machines," he said.

For Mr Tham, his employees have always been the company's biggest asset. Currently, a diverse mix of 2,900 people from more than 50 countries serve KPMG in various roles as accountants, data scientists, oil and gas experts, engineers and game developers.

"You cannot have happy clients unless you first have happy workers," he said.

Mr Tham always insisted on the company accounting for its staff as an asset. His persuasion bore fruit when the company agreed to measure staff turnover each month, just as they would measure profits or losses. The result has been a boost in employee morale and, in turn, in business.

KPMG has a number of recreational activities and facilities to help employees relax, including a 5,000 sq ft clubhouse in Robinson Road. Last week's anniversary party was a gala event for the staff, with concerts and entertainment, dinner and dance at Marina Bay Sands.

A day later, they held their annual Make A Difference Day, where staff reached out to the community to work with any charity of their choice to organise and execute a fun day for beneficiaries like the elderly and people with disabilities.

This is an issue close to Mr Tham's heart. "We cannot earn the trust of the society at large unless we show that we care for the community," he said.

Trust, he believes, is the bedrock of the accounting profession and, in this context, absolute integrity from the staff in all work KPMG does is a given. So is responsibility in their actions at work and in their personal lives. "As a profession that operates on trust, we need to do our part," he said.

While he loves his job, Mr Tham said he is ready to pass on the baton. "I set about implementing my succession plan from day one," he said, refering to the day he took over the leadership mantle.

The job requires tremendous discipline, with decisions taken to benefit the current generation and next. "That succession planning is virtually complete for me," he said, without divulging details.