In Zanzibar, which the State Department rates as a "hardship post," the U.S. government provided Mary Cardozo, a Foreign Service secretary, and her husband with a two-bedroom apartment, two full-time servants, access to the embassy's swimming pool and tennis courts, air-delivered fresh foods and inexpensive liquor.

In Washington, which the British once classified as a hardship post, the lifestyle of Mary Cardozo, oddly enough, figures in a case pending before the Supreme Court.

The key issue is a requirement in the Foreign Service Act of 1946 for retirement at age 60, compared with 70 in the civil Service retirement system.

Of the more than 58,000 government employes working overseas in 1976, 4,800 faced mandatory retirement at 60. They were employed by the State Department, the Agency for International Development and the U.S. Information Agency.

Claiming that forced earlier retirement denied them the equal protection of the laws guaranteed by the Constitution, 10 persons in the Foreign Service who were or will be forced to step down sued in U.S. District Court here.

The State Department defended the system, claiming that some Foreign Service personnel work in "isolated, primitive or dangerous areas" characterized by poor housing, unsafe foods, substandard sanitation and debilitating physical and psychological stress.

That's all in the past, the plaintiffs contended. They said that nearly all Foreign Service personnel have "white-collar desk jobs" and enjoy housing and sanitation that is "never substandard and is frequently superior to that enjoyed.

Using Cardozo's lifestyle in Zanzibar as an by Civil Service employes in the United States." example, they said that "many of these 'hardship posts' have other amenities not available to the majority of Washington civil servants - e.g., low-cost household help, unpolluted beaches, private tennis courts paid for by the U.S. government, inexpensive liquor and food, slower pace of life and high status in the local community."

Last June, a three-judge panel found it "patently arbitrary and irrational" to require Foreign Service personnel to retire 10 years earlier than Civil Service personnel.