Jim began his career as an archivist in the Public Record Office of Northern Ireland, where his role included responsibility for archives conservation. 

He was appointed Head of Conservation at the Ulster Museum in 1991 and held the position for 15 years, during which time he developed a particular interest in preventive conservation of the Museum's diverse collections.

In 2006, he became the first Director of Collections at National Museums Northern Ireland, a role which encompassed all collections and collections-based activities at the Ulster Museum, the Ulster Folk and Transport Museum and the Ulster American Folk Park. This involved oversight of such areas as exhibitions and associated public programmes, preservation of collections and collections accountability. Prior to his retirement in 2015, he was Acting Chief Executive for National Museums Northern Ireland. 

In his earlier academic career, Jim gained a PhD from Queen's University Belfast (1982) and held postdoctoral positions at University College London (1982-3) and the Queen's University Belfast Institute of Irish Studies (1983-4). He has published widely on the subject of stone deterioration and was appointed Honorary Research Fellow at Queen's in 1998.