William P. Benson, 82, a retired senior vice president and comptroller of the B.F. Saul Co., mortgage bankers and realtors, died at his home in Rockville Saturday following a heart attack.

Mr. Benson was born on a farm at Neelsville in Montgomery County. He graduated from Germantown High School in 1914 and then moved to Washington. He got a job as a Western Union messenger and also attended Benjamin Franklin University, where he earned a certificate in accounting.

In 1914, Mr. Benson became a teller at the Home Savings Bank, which had been organized by B.F. Saul. The bank later merged with the American Security and Trust Co.

In 1919, Mr. Benson joined the B.F. Saul Co. Following his retirement from it in 1966, he was a member of the board of directors of the B.F. Saul Real Estate Investment Trust until last year.

Mr. Benson was a member of the First Congregational Church in Washington and had served as chairman of its board of trustees. He also was a member of the Metropolitan Washington YMCA and had served as chairman of its finance and building committees.

Survivors include his wife, the former Mary Jane Johnson, with whom he had graduated from high school and to whom he was married for 61 years, Rockville; two sons, Dr. William P. Jr., of Baltimore and C. Herbert, of Arlington; three daughters, Betty Coleman of Devon, Pa., Mary Jane Beem of Scarborough, N.Y., and Carol Milligan of Sidney, Ohio; two sisters, Kathleen Benson and Mrs. Jacob Snyder, both of Gaithersburg; 17 grandchildren, and six great-grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to St. Paul's United Methodist Church of Kensington.