McGuire was also the founding editor of International Quarterly and an associate at Lombard Street Research, an economics consultancy in the City of London.
Before going to work for Newsweek in 1978, McGuire spent eight years at the now-defunct San Antonio Light, where he won a series of state and national honors while heading the paper’s investigative-reporting team.
Simpson trial, the magazine's reporting on the fast-expanding entertainment industry and immigration issues, as well as major disasters such as the Southern California brush fires of 1993 and the 1994 Northridge earthquake.
As London bureau chief, McGuire covered a number of political, economic, cultural and social developments, from Iberia to Scandinavia to Eastern Europe.
In December 2009, McGuire gave testimony to the House of Commons Foreign Affairs Committee as part of its inquiry into Global Security: UK-US Relations.