 He is not to be confused with the British exploration geologist Christian O'Brien (1914-2001).After succeeding to his brother's peerage, he returned to Ireland where he maintained Thomond House on the former ancestral estate of Dromoland Castle, and a smaller home in England at Richard's Castle near Ludlow.On 19 February 1945 he married Vera Maud Winter, the daughter of Reverend Clifton Winter.