Career
He is best known for managing Linfield between 1997 and 2014. He began his professional playing career with the club, following a spell in the Manchester United youth team, and also played for Ards and Larne. Born in Newtownards, Jeffrey began his football career as a schoolboy with Manchester United, but never played in the first team
He joined Linfield in the summer of 1982.
He played for Linfield for 10 years and was club captain for much of that time. Jeffrey scored the crucial away goal against Shamrock Rovers in the 1984-1985 European Cup.
He left Windsor Park for his hometown club, Ards in the summer of 1992 reuniting him with former boss Roy Coyle and in February 1995 joined Larne as player-coach. Linfield
In April 1996, Jeffrey returned to Linfield as assistant manager to Trevor Anderson.
Jeffrey was appointed as Linfield manager on 4 January 1997 after Anderson resigned.
In the 2005-2006 season, Jeffrey guided Linfield to a clean sweep of domestic trophies, missing out only on the cross-border All-Ireland Cup. On 6 June 2006, Jeffrey signed a new four-year contract, the longest contract in Linfield history. His previous deal had one season left to run.
By January 2014, he had extended this record to 32 awards.
On 15 February 2014, Jeffrey announced that he was to step down as manager of Linfield at the end of the 2013-2014 season. He was replaced by former Northern Ireland international, Warren Feeney.
Ballymena United
On 7 March 2016, it was announced that Jeffrey had been appointed the new manager of Ballymena United, following the sacking of Glenn Ferguson. Irish Premier League/IFA Premiership (9): 1999–2000, 2000-2001, 2003-2004, 2005-2006, 2006-2007, 2007-2008, 2009-2010, 2010-2011, 2011-2012
Irish Cup (7): 2001-2002, 2005-2006, 2006-2007, 2007-2008, 2009-2010, 2010-2011, 2011-2012
Irish League Cup (6): 1997-1998, 1998-1999, 1999–2000, 2001-2002, 2005-2006, 2007-2008
County Antrim Shield (6): 1997-1998, 2000-2001, 2003-2004, 2004-2005, 2005-2006, 2013-2014
Setanta Cup (1): 2005
Irish League Floodlit Cup (1): 1997-1998
Jeffrey, who lives in Glengormley, has a career in social work alongside his football interests.