Elliott was appointed to his U.S. dplomatic post in November 2019. His previous diplomatic post was as head of the Office of the Northern Ireland Executive in Brussels from 2015 until November 2019, where a major priority related to the particular challenge of Brexit for the region of Northern Ireland.
From 2010, Elliott was responsible for a programme of major reform to the delivery of EU Common Agricultural Policy grants and subsidies to farmers in the Department of Agriculture and Rural Development in Northern Ireland. As a result of this work, the exposure of the Department to financial correction by the European Commission was significantly reduced.
Previously, Elliott was secretary to the Parades Commission with responsibility for providing senior advice to the Commission on the discharge of its duties and powers in relation to issues concerning human rights and the promotion of mediation and peace-building.