Cyril Sidebottom was born on 17 Dec 1877 at Morven (Evandale), the fifth son of William Sidebottom, MHA for Selby and a bark merchant, and his wife Sarah Jane Bull (1844-1893). Cyril was educated at the Launceston High School in Milton Hall, Frederick Street. He won prizes for running while still at school and later played football for the Launceston Football Club. Cyril married Ethel May Sidebottom who was born in Sydney in 1928, daughter of Moses and Charlotte Sidebottom.
Cyril worked for the National Bank in Launceston and moved to Victoria about 1918. He was acquitted of stealing money from his employer, the Bank of New Zealand, in 1921 but was later insolvent as a result of the case. His wife Ethel May died on 21 Feb 1928 at Glen Iris in Melbourne and Cyril died seven months later at Malvern on 22 Sep 1928.