At least one Harvard man knows what it's like to go on dates with Secret Service men. Edward Cox, one of Tricia Nixon's current beaux, has enrolled this fall as a first-year student at the Law School.

Cox, who escorted Tricia at the Republican National Convention last summer, cut short his summer work this year to visit the Nixons in San Clemente, Cal.

While at the Western White House, Cox surfed with Tricia and went to a baseball game with Tricia, her younger sister Julie, and Julie's husband, David Eisenhower. When a picture of the four appeared in newspapers, Eastern columnists reported that Cox was Tricia's"favorite date," ahead of contenders like Barry Goldwater Jr.

Former Tiger

Cox graduated from Princeton in 1968 and studied at Yale's Art and Architecture school last year. He was one of the original "Nader's Raiders" who studied the Federal Trade Commission in the summer of 1968 and issued a denunciatory report last February. Until his trip to California this summer, Cox continued his work for Nader and also served as a summer intern for The New Republic, a liberal magazine.

At Princeton, Cox was undergraduate commander of ROTC units. His father is a caeer Army officer from New York.

Tricia, who once encouraged Georgia's Governor Lester Maddox to turn his chicken restaurant into a private club to avoid Federal civil rights laws, is reportedly the most conservative member of the Nixon family. Washington columnists say that Cox is politically left of both Tricia and her father. But they add that President Nixon enjoys the "give-and-take" of discussing social issues with Cox.