It was just that...MEN ONLY.

(From United.com....http://www.united.com/page/article/0,,3302,00.html)

"Business as usual--1950s style:
United in 1953 introduced "Executive" all-male passenger flights. The men enjoyed free gifts such as cigars, which the stewardesses often lit for them. A reporter for Playboy magazine wrote, ". . .the only girls aboard are a couple of unobtrusive stewardesses. . ."
The popular Executive flights flew 10,500 segments, with a load factor of 80 to 90 percent, from 1953 until they were discontinued in 1970.
Complimentary alcohol, measured in cruets, was added to first class flights in 1956, and passengers were restricted to a two-drink limit. Stewardesses monitored the drink ration."