Frank was born in Baltimore City, Maryland on 10th May 1858, the son of John and Mary (née Gleason) Flannery. His parents were both born in the parish of Kilruane, near Nenagh, County Tipperary, and emigrated to the U.S.A. as children.
Frank was educated in the University of Niagara, the University of Maryland and Johns Hopkins University (from which latter he graduated in 1880). He was thoroughly equipped by training and study for the successful practice of his chosen profession, that of medicine. Shortly after his graduation he was appointed first assistant resident physician at the University Hospital, serving for two years, when he resigned to accept the appointment of a second assistant at Mount Hope Retreat under Dr. Stokes.
From 1883 to 1890 he was physician in chief of St. Vincent's Infants' Asylum and lying-in hospital. During this period he was a member of the medical corps of the health department of the city of Baltimore, was assistant chief of the University Hospital Dispensary and also took a very prominent part in the smallpox epidemic of 1882.
He was twice elected coroner for the Southern District, but during the second term resigned in order to take charge of the Maryland Penitentiary. The latter position he also resigned in 1890, when he was made resident physician of Mount Hope Retreat and physician in charge of St. Vincent Sanitarium.
Mount Hope Retreat was intended especially for the reception and care of the insane, but received patients of every description, whether suffering from mental or physical disorders. It is surrounded by a fine estate of more than three hundred acres, and is one of the most complete and magnificent edifices of its kind. Frank held the position of resident physician from 1890 until 1936.
He maintained close connections with the Clinical and Alumni Association of Maryland and Virginia, and was a member of the Baltimore County Medical Society, the Neurological Association of Baltimore, the Golden Chain and several benevolent associations.
Frank married Ella Brannon (second daughter of Henry Brannon, supreme judge of West Virginia), and the couple had a daughter named Ella. They lived at 4212 Patterson Avenue. He died on 11th March 1936 at St. Agnes Hospital, and was buried in the New Cathedral Cemetery, Baltimore.
[his portrait is sought]