Langstone was the fourth of five children. His father deserted the family while he was still young and his mother died in 1890, leaving his sister to raise the family. Young Frank was placed in foster care.
About 1906 he began his restaurant business, which continued for many years. In 1919 he ran for Parliament, but was not elected until 1922. He remained in Parliament, but not continuously, until 1949, in the Labour party. He later also ran several times, unsuccessfully, as a Social Credit Political League candidate. Held several ministerial posts and was briefly high commissioner in Canada.
He married twice and had five children.