Lorimer Arthur Davidson, 97, a Rockville resident who was a retired board chairman, chief executive officer and president of the Government Employees Insurance Co. (Geico), died of pneumonia Nov. 27 at Suburban Hospital.

In 1948, in association with David Lloyd Kreeger, he formed a syndicate that bought 75 percent of the stock of Geico and became the company's senior investment officer.

He became president in 1958 and board chairman in 1964. He retired as president and chairman in 1970 and from the corporate board in 1978.

Over the years, Mr. Davidson had served on the boards of various Geico companies, as well as on the board of Riggs National Bank. He also had served on the advisory board of the Washington Mutual Investors Fund and was a member of the Washington Society of Investment Analysts.

He had served on the vestry of St. Alban's Church in Washington and had been a trustee of Suburban Hospital.

He was a trustee emeritus of the Federal City Council and the Suburban Health Foundation and a member of the Alfalfa and Columbia Country clubs.

Mr. Davidson, who was born in Granby, Quebec, came to the United States in 1924.He worked on Wall Street as a trader and bond salesman before serving as an artillery officer in the Canadian Army during World War II.

A 1978 profile of Mr. Davidson in The Washington Post said that during his years of leadership, he formed affiliates in related businesses that made Geico a nationwide business and helped early Geico investors reap a fortune.

In 1976, when Geico entered troublesome financial times, he came out of semi-retirement to accept membership on a select company committee that successfully sought new leadership for the insurance giant.

Mr. Davidson saw the company grow from one with assets of $4 million in 1948 to about $1 billion in 1978. He told The Post in 1978 that the main factor in his view in the company's success was "high-quality insurance at lower rates, with no agents."

His wife, the former Betty Gael Valentine, whom he married in 1927, died in 1995.

Survivors include a son, Thomas F. Davidson II of Ogden, Utah; three grandchildren; and nine great-grandchildren.