NEW YORK—About 300 people gathered last week to honor Robert Clements, an insurance industry veteran who died in September at the age of 77.

Various heavy hitters spoke during the memorial at New York's Waldorf=Astoria Hotel about how Mr. Clements influenced them since he joined the industry in 1957.

The group included son John Clements and leaders of companies in which the elder Mr. Clements was involved: Peter Garvey of Integro Insurance Brokers Ltd., Dinos Iordanou of Arch Capital Group Ltd., Kevin Kelley and Mitch Blaser of Ironshore Inc., Brian Duperreault of Marsh & McLennan Cos. Inc., Evan G. Greenberg of ACE Ltd. and former XL Capital Ltd. executive Brian O'Hara.

Mr. Duperreault, president and CEO of MMC, described how Mr. Clements helped set up companies such as ACE in Bermuda, transforming not only the island but also the industry.

“I wouldn't have been chairman and CEO of ACE without Bob's genius,” Mr. Duperreault said. “When I think about what I need to do at and for Marsh, I'm inspired by Bob. His influence will carry on for years.”

Mr. O'Hara, former chairman and CEO of XL, another Bermuda company that Mr. Clements helped set up, said Mr. Clements taught him that the most important rule was the strength of the value proposition with the customer. “If you're living up to your promises better than the competition, your customers will see you through large losses in difficult times,” Mr. O'Hara said.

Mr. Iordanou, chairman, president and CEO of Arch Capital Group, described Mr. Clements as a “college professor” type who rarely wore a tie and favored a sports coat, corduroy pants and comfortable shoes.

Mr. Clements was a lifelong Democrat and Mr. Iordanou has been a lifelong Republican. When Mr. Iordonou said to his friend one day that they'd agree on almost everything if it weren't for politics, Mr. Clements gave him a penetrating look before responding calmly. Mr. Iordanou was looking at it the wrong way, he recounted Mr. Clements saying: The world isn't flat—it's round; it just happened that Mr. Iordanou was standing at immediately before noon and Mr. Clements at a minute past noon. Technically, they were close to each other and holding hands.

“I didn't quite know what he meant and I never had the courage to ask,” Mr. Iordanou said. “But it tells you as to how he thought about issues.”

Mr. Garvey, Integro's president and CEO, was among those who remembered Mr. Clements' habit of pausing in the middle of his conversation. Like many people, Mr. Garvey couldn't restrain himself from finishing Mr. Clements' sentences, only to discover in embarrassment that he had no idea what Mr. Clements intended to say.

“Bob loved words and knew the power of picking the correct ones. He wanted to make sure you were listening closely. As a leader, Bob knew how to grab your attention,” Mr. Garvey said.

Mr. Greenberg, CEO of ACE, said his company owed its growth from a single employee out of a hotel room in Bermuda to a 25-year-old global company to Mr. Clements. “It wouldn't have been possible if Bob hadn't thought outside the box,” Mr. Greenberg said.

Mr. Kelley, CEO of Ironshore, pointed out that Mr. Clements left a “powerful impact” on the lives of many people.

“The last I looked, Bermuda was still overloaded with those that follow Bob—a sure sign of flattery,” said Mr. Blaser, chief operating officer and chief financial officer of Ironshore Inc. and CEO of Ironshore's Bermuda office. He said that the last time they met, Mr. Clements asked him when he thought the market would turn.

John Clements, managing partner of Tara Partners Ltd., a private investment partnership that co-founded Integro Ltd. and Ironshore, recalled that his father once considered giving up insurance to open his own restaurant and become a chef.

“Fortunately, that's a venture that never got off the ground,” he said.