Vaughan correctly pointed to the importance of the fact that John George’s father, George Adair, had married into the powerful and influential Trench family. In particular, his interaction with the ruthless land agent William Steuart Trench is thought to have influenced Adair’s outlook on how to deal with recalcitrant tenants. No attention, however, has been given to the fact that John George’s grandfather, John Adair of Rath, Queen’s County, had married Rebecca Maquay, a member of a rich and powerful Dublin-based sugar-merchant and banking family. Two of the Maquays became governors of the Bank of Ireland and one of them, George, had a canal bridge in Dublin named after him. Eventually, a member of this family circle, John Leland Maquay (1791–1868) moved to Florence and established a banking firm there in 1840. This banking firm of Pakenham & Maquay expanded and had branches in Rome, elsewhere in Italy and beyond.
In the British Institute Library in Florence are to be found, inter alia, the diaries of John Leland Maquay and of his wife, Elena, and correspondence relating to the Trinidad sugar plantations that had been owned by John Adair, uncle to John George, who died in 1839. On the death of John Adair, these sugar plantations were inherited by John George’s father. John Leland Maquay visited Ireland in 1840 and 1842 to sort out issues of inheritance and business relating to them. During those visits Maquay encountered the young John George Adair. In October 1843, having recently taken his degree at Trinity College, Dublin, John George made his first visit to the Maquay household in Florence. He stayed there—apart from a short interlude in Rome—for nine months. This was to be the first of many visits between 1843 and 1862, and J.L. Maquay records Adair’s activities in Florence over this twenty-year period. On one occasion Adair encountered Charles Lever, the famous novelist, and the two became such friends that Adair was appointed as an executor of Lever’s will.