Harriet Thurtell never married. She was extremely interested in the Thurtell family history and worked a great deal on it. She visited Hobland Hall, Suffolk, England, and painted a picture of it which is in the home of Susan Persia Thurtell Miller. She also completed a family tree, a photocopy of which is in the possession of Susan Miller.

Her name is sometimes spelled Harriet, but she spells it Harriett in a letter to her nephew, Henry (Harry) Thurtell at the time she sent him the copy of the rough draft of the family tree.

She is buried in Woodlawn Cemetery in Guelph, Ontario, Canada.

Harriet’s obituary states:
Laid to Rest. Miss Harriet Thurtell, only surviving daughter of the late Benjamin Thurtell of Guelph, passed away the fifth of March at the residence of Prof. Ellis of Toronto University. The funeral service took place at Prof. Ellis’ residence, 74 St. Alban’s Street, Toronto. Mrs. Ellis being a niece of the deceased. The body arrived in Guelph by the Grand Trunk train at Union Cemetery, Archdeacon Davidson, of St. George’s officiating. Mr. Guy Thurtell of Guelph Township, is a nephew of the late Miss Thurtell and her two nephews Messrs. Geo. and H. W. Mickle, from Toronto were among the mourners. The Mickles were brought up on the Guelph Township farm, which used to be known as Mount St. Patrick. (A note from Charlotte Unangst Mackie clarifies that Union Cemetery, Guelph, was renamed Woodlawn Cemetery in 1925.)