Mr. Backer, who died in 2016, was known especially for his Coca-Cola campaign at McCann-Erickson. A lapsed lyricist, he had co-written the hymn “I’d Like to Teach the World to Sing (in Perfect Harmony),” which he turned into, “I’d Like to Buy the World a Coke and Keep It Company.” He also coined slogans, like “Things go better with Coke.” Backer & Spielvogel did not seek traditional small-agency start-up accounts. Rather, they took big-name clients away from giant rivals. They also picked up four more partners from Interpublic or McCann-Erickson. The six principals resolved to limit their client list to 15, and agreed that their ads should build the personality of each client, not the agency’s. By 1981, Backer & Spielvogel had nine clients, including Campbell’s Soup, with $20 million in billings, and the Paddington Corporation (J & B Rare Scotch), another $20 million. More were added later, including Seven-Up, Helene Curtis, Philip Morris, Quaker Oats, NCR Corporation, Hyundai, Arby’s and Magnavox. In 1986, the agency was bought by the British company Saatchi & Saatchi for more than $100 million ($56 million down and $45 million paid over six years), and in 1987 it merged with Ted Bates Worldwide. Backer Spielvogel Bates Worldwide grew into the world’s third largest ad agency, with 8,500 employees and 178 companies in 55 countries.