Harrison became a football coach and worked at Everton before he was brought to Manchester United by Ron Atkinson in 1981 to manage the youth team.
Under Alex Ferguson, Harrison developed "one of the best crops of young players in the English game" – the so-called Fergie's Fledglings – which included David Beckham, Ryan Giggs, Paul Scholes and Gary Neville.
At Barrow, he was noted as a strong midfield player who played a key role in securing the club's promotion to the Third Division in 1967.
Dissatisfied with the number of players coming through the United youth system, Ferguson called a meeting with Harrison to discuss potential improvements.
Other players brought through the Manchester United youth team by Harrison include Mark Hughes, Norman Whiteside, Clayton Blackmore and Graeme Hogg.
[3] In 1998, Harrison retired as youth team manager but continued as coaching co-ordinator, working with groups from the under-nines to the under-16s,[8] until he left Manchester United around 2008.