Gertrude married Dr John MacNamara and moved to Corofin, County Clare, in 1922 and took Harbison with them.
Holidays at that time were with her father's brother, Henry MacSherry, in Eastbourne where she learned to play tennis.
In 1967, Harbison inherited Inchiquin House from her aunt in Corofin,[3] but the following year her husband died.
She wrote her dissertation on Geoffrey de Geneville under the supervision of Professor James Lydon.
[1][4][2] Harbison earned her degree in 1972 and went on to complete a master's which was written on William of Windsor in Ireland, 1369–76, and graduated in 1977.