[1] He was educated at Ludgrove, Eton and Trinity College, Cambridge.
[2][3] Cairns was Managing Director of S. G. Warburg & Co. between 1979 and 1985, of Mercury Securities plc between 1981 and 1984, Chairman of Voluntary Service Overseas (VSO) between 1981 and 1992, Vice-Chairman of Mercury Securities plc between 1984 and 1986, and a Director of S. G. Warburg & Co. between 1985 and 1995.
[3] He was appointed Chairman of the African telecommunications company Celtel in October 2007 and was a board member of the charity The Mo Ibrahim Foundation until 2016, alongside Mary Robinson and Kofi Annan.
[5] He was invested as a Commander, Order of the British Empire (CBE), in 1992.
Cairns was invested as a Commander of the Royal Victorian Order (C.V.O.)