Dame Judith was British High Commissioner to South Africa from September 2013 until March 2017, when she retired from the Foreign and Commonwealth Office after a career of some 40 years in the Diplomatic Service. After graduating from Oxford University and a year in Romania as a British Council scholar, Dame Judith entered the Foreign and Commonwealth Office (FCO) in 1976 serving first in the former Yugoslavia, and later as First Secretary in Prague and Paris. In her early years in the FCO, she held various posts dealing with Poland, Western Europe, and as the Secretary of State's speechwriter. After serving as Ambassador to Slovakia from 2004-7, she was appointed FCO Director for Migration from 2007-9 and then Ambassador to Mexico in 2009, for which she was awarded the CMG. In 2013, she became British High Commissioner to South Africa, Lesotho and Swaziland. She was awarded the DCMG for her services to Diplomacy in January 2016.
Since leaving the Diplomatic Service, and in addition to the BTA, Dame Judith has taken up a number of Board positions, including as Independent Non Executive Director for the UK/Mexican company Fresnillo plc, as Member of the Arts and Humanities Research Council and as Vice Chair of Southampton University. In 2020, Dame Judith was appointed Chair of the Strategic Advisory Group to the Global Challenges Research Fund.