Captain Richard Scougall Cassels was born on October 5, 1859 at Holland House, Quebec, son of Robert Cassels and Mary Gibbons Macnab. He obtained a degree from the University of Toronto and went to Osgoode Hall, being called to the Ontario bar in 1883.

He served as a Lieutenant with the Queen’s Own Rifles and participated in the North West Field Force in 1885 [see transcription of the Diary of Lieut. R. S. Cassels North-West Field Force, 1885] but retired from the QOR effective 22 October 1886. In 1892 was a founding officer of the 48th Highlanders of Canada, a regiment in which he was promoted Captain. He later became a life member of the Royal Canadian Military Institute.

He was a partner in the Toronto law firm of Cassels, Brock & Kelley, which later became Cassels, Brock & Blackwell, and he practised law for 52 years. He was appointed a King’s Counsel in 1910. Cassels was a keen amateur photographer as well, being active in the Toronto Camera Club for many years. He produced the photographs of wildflowers for the 1930 manual produced by J. E. Jones, entitled Some Familiar Wild Flowers. His slides and photographs of botanical specimens was left to the Botany Department of the University of Toronto. He resided at 93 Bedford Road, Toronto, at the time of his death on 17 July 1935 and is buried in St, James Cemetery, Toronto.