Lennie began his career as a junior at Brentford and embarked on a scholarship at the beginning of the 2002–03 season.[2] He received his maiden call into the first team squad for a Football League Trophy first round match versus Barnet on 14 October 2003 and remained an unused substitute during the shootout win.[3] Lennie was an unused substitute on another four occasions during the 2003–04 season.[3] Lennie made his professional debut in a Football League Trophy first round match versus Milton Keynes Dons on 28 September 2004.[4] With the game already lost at 3–0, Lennie came on as a half-time substitute for Alan Julian.[4] He was called into the first team squad on another six occasions during the 2004–05 season, but did not play.[5] Lennie was released at the end of the 2004–05 season.[6]
^First North Signings. "First North Signings". The Evo-Stik League Northern Premier. Archived from the original on 26 July 2014. Retrieved 17 August 2014.