Gertrude Tinsman Sorel, 71, a retired head mistress of the Lower School of the Potomac School in McLean, died of cancer Sept. 28 at a nursing home in Kings Park, N.Y.

Mrs. Sorel lived in Washington before moving to New York about 10 months ago to be near a sister, Catherine T. Speh of Setauket, N.Y.

She came to Washington in 1943, after marrying Paul Sorel, who was head of the book service at the Virginia Theological Seminary in Alexandria. He died in 1979.

In 1947, Mrs. Sorel began teaching at Potomac School, a private school then located in Washington. In 1963, she was made head of the Lower School, which includes prekindergarten classes through the third grade. She retired in 1972.

She then worked as a volunteer at the complaint center at the District Building in Washington.

Mrs. Sorel was born in St. Louis and earned a bachelor's degree from Wayne State University in Detroit. She taught public school in Cleveland, worked for the Works Progress Administration in the mid-1930s and was a volunteer for the American Red Cross during World War II.

She was a member of Christ Episcopal Church here.

Besides her sister, survivors include a brother, Gordon L. Tinsman of Peoria, Ill.