John Grant, of Kilgraston married, in March 1828, Lucy, daughter of Thomas, 7th Earl of Elgin and 11th of Kincardine. His father-in-law was Ambassador to the Ottoman Empire from 1799 to 1803, and famously obtained a firman from the Ottoman Sultan for the removal of a large collection of marble sculptures from the Parthenon, which he brought back to Britain in 1806. The 'Elgin Marbles' were deposited in the British Museum in 1816 and were moved to the purpose-built Duveen Gallery in 1936.