Politician, lawyer and businessman. Born on the island of Bute, Bannatyne was the son of a Glasgow postmaster. Educated in Glasgow, Edinburgh and Heidelberg (Germany), he entered a Glasgow legal firm at the age of 15 and then moved to Edinburgh to finish his apprenticeship. By 1825 had joined the Faculty of Procurators and he served as Dean of the Faculty from 1860-65.
Bannatyne was involved in various business enterprises; he brought the Edinburgh and Glasgow Railway Company into being. He was a supporter of parliamentary and municipal reform, promoted the Bankrupt Act of 1839 and the Procurators' Act of 1865. In 1866, he was a commissioner on the inquiry into the registration of heritable property.
He was granted an honorary degree by the University of Glasgow in 1868.
Bannatyne died at his home, Milheugh, in Blantyre.