Gray provided services to accounts that included the American Petroleum Institute, Procter and Gamble, and the National Association of Broadcasters and El Paso Natural Gas.

Notable clients of Gray and Company included Adnan Khashoggi, Saudi Arabian billionaire and arms dealer, the government of Haiti under the Duvalier dynasty, American commodities trader and financier Marc Rich (who in 1983 was indicted for trading with Iran during the hostage crisis and a variety of other charges, fled the country, and was later granted a pardon by President Bill Clinton), the Teamsters Union, and Korean religious leader Sun Myung Moon.

[4][5] Gray's first book, Eighteen Acres Under Glass: Life in Washington As Seen By the Former Secretary of the Cabinet, was published in 1962 by Doubleday in the States and by MacMillan overseas.

Eventually becoming number four on The Times best-seller list, the book highlighted the demands on both his political and social life as the Secretary of the Cabinet under President Dwight D. Eisenhower.

Gray was featured in cover stories in Time magazine and U.S. News & World Report, and was the subject of a fifteen-minute Monitor program on NBC.