BARON LEON LAMBERT, 58, who had headed Groupe Bruxelles Lambert, Belgium's second largest holding company, for 38 years before retiring this year, and who was a top executive in its U.S. affiliate, Drexel Burnham Lambert Inc., died May 28 at a hospital in Brussels. The cause of death was not reported.

The Belgian firm was recently connected to a Securities and Exchange Commission investigation of Drexel Burnham Lambert for alleged insider trading. Groupe Bruxelles has denied any wrongdoing.

He also was a 1971 cofounder of Artemis, an international art investment trust. His personal collection included works by Giacometti, Rodin, Degas, Bonnard and Belgian surrealists Rene Magritte and Paul Delvaux.

LUCILE S. PACKARD,

72, the wife of Hewlett-Packard board chairman David Packard and a major Silicon Valley philanthropist, died of cancer May 30 in Los Altos Hills, Calif.

She and her husband, whom she married in 1938, met while they were attending Stanford University. The Packards gave millions to a variety of causes, including Stanford's Children's Hospital, where Mrs. Packard was board chairman, the Monterey Bay Aquarium and the San Jose Museum of Art.

JAMES E. THOMAS III,

41, a former assistant metropolitan editor of the Baltimore Sun and a 1974 graduate of the University of Maryland who recently resigned from the paper to accompany his wife, Ellen Uzelar, to her new assignment as The Sun's West Coast reporter, died of cancer May 30 in San Francisco.

Mr. Thomas entered the newspaper business as a reporter and editor with a weekly in Columbia. He later was an editor at the Hagerstown Daily Mail and was a night editor at the Baltimore News-American before joining The Sun last summer.