Most notably, she was a student of Hamilton Technical School in where her mentor was Hortense Gordon. Holbrook, whose early interest was in painting, is said to have developed a penchant for sculpture at the Ontario College of Art (now OCAD) where her instructor was Emanuel Hahn. In 1935, when Holbrook matriculated from OCAD, she became Hahn’s assistant.

Holbrook’s early commissions, including a bust of international humanitarian Dr. James H. Robinson and Frank Panabaker, raised her visibility as an artist. In 1948, she had the opportunity to serve as assistant to renowned Swedish sculptor Carl Milles at Cranbrook Academy of Fine Arts. During this time, Holbrook learned how to construct large scale sculptural projects—that process led to even greater recognition for the artist.

Holbrook’s most memorable public images include stone reliefs for the facade of a Federal Building located in Canada. The art-deco inspired panels highlight Canadian industry and animals such as caribou and black bears. Similar to Diego Rivera, Holbrook used the power of her art to highlight the working class. Holbrook, who worked until at least age 86, mentored countless students including sculptor Christian Cardell Corbet who restored her reliefs at the Federal Building.

The artist’s numerous other public commissions including a 1954 Bears panel for the Hamilton Public Library and a bust of Irish playwright James Bernard Shaw. Although Holbrook spent the majority of her life in Hamilton, she considered the city inhospitable to women artist at times. However, she continued to be active in the Hamilton arts scene and to support upcoming artists throughout her career.