Duffy followed Charlton's youth team manager Terry Westley to Rushden & Diamonds in 2001, where he made over 30 appearances, most as a substitute.
[2][3] He struggled to regain form,[1] was loaned to non-league club Stamford and had short spells with Cambridge United and Kettering Town before joining Gainsborough Trinity in January 2006.
[5] Duffy was recommended to Oxford United by former youth development officer, Malcolm Elias, and joined the club on a one-month trial in July 2006.
[9] Duffy was placed on the transfer list in January 2008 as manager Darren Patterson tried to free up funds to bring in new players,[10] and joined Wrexham on loan later that month.
[13] He was released by Oxford at the end of the season and, after an unsuccessful trial at Mansfield Town, he signed for Conference South side Newport County in July 2008.
[19] On 16 May 2011 Town chairman John Fenty mentioned that the club had made a mistake in signing Duffy and teammates Charles Ademeno and Serge Makofo.