 Millar was made a KCMG in 1949 and a GCMG in 1956, and in 1962 he was raised to the peerage as Baron Inchyra, of St Madoes in the County of Perth.Lord Inchyra married in 1931 "Jonkvrouw" Anna Judith Elisabeth de Marees van Swinderen (1906–1999), daughter of "Jonkheer" René de Marees van Swinderen, Dutch former Minister of Foreign Affairs (1908–13) and Ambassador in London (1913–37).They had four children, two sons and two daughters.