Enfield youngster Greg Heald played 11 times for the Norwich City youth side in 1989/90 adding to his two appearances the previous season. After failing to break into the Norwich first team, he returned to play for his hometown club. He left Enfield to join Peterborough and by the start of the 1997/98 season had made 105 league appearances for the Posh scoring 6 times.

He joined Barnet, as their record signing, in the early part of the 1997/98 season and scored on an early appearance in the 3-1 Coca Cola Cup victory over Norwich City. He made 43 appearances during 1997/98 scoring three goals. Barnet were relegated to the Conference on 5th May 2001 despite Heald's efforts in the 39 league games he played (taking his total to 141 games and 13 goals). As a result of the relegation, every player at Underhill was placed on the transfer list. In April 2002, Greg was selected for the England non-league international side to play Holland on April 24th

On March 27th 2003 (Transfer Deadline Day), Barnet were forced by financial pressures to sell Heald and teammate Wayne Purser to Leyton Orient for a joint fee of £18000. In the summer of 2003, Orient manager Paul Brush honoured Greg's talents and leadership by naming him club captain for the forthcoming season.

Under new manager Martin Ling, Greg was unable to secure a regular first team place at Orient, especially following the signing of John Mackie from Reading in January 2004. On March 15th 2004, Greg was released from his contract in order that he could join Rochdale until the end of the 2003/04 season. Another year with Rochdale followed but he was released in June 2005. He was reported to have signed for York City at the beginning of July 2005 but later backed out of the deal.

Greg signed for Burton Albion and played in their opening day Conference clash with Grays Athletic on 13th August 2005. Two days later though, he transferred to Unibond Premier Division side Ashton United who had offered him the security of a one year contract. He moved on again on 31st August, joining Conference strugglers Aldershot.

on 27th March 2006, 34 year old Greg quit Aldershot and professional football stating that "I have got some studies to concentrate on and some future work and I have to look to the future," as he prepares for a life outside of the game as a teacher. However on 16th June 2006, Greg signed for Conference South side Thurrock.

On 18th July 2007, Greg was appointed youth team manager of Wycombe Wanderers replacing the promoted Ian Culverhouse.

Greg signed for Enfield Town in January 2008 and made his debut in the 1-0 Ryman League defeat to Wingate and Finchley. He is a full-time teacher at the Lattymer School.