After working his way through the junior grades at Cronulla Lennon moved to the St. George Dragons before he signed for English club the Castleford Tigers while still twenty years of age.

After signing for the Castleford Tigers in 2001 Lennon quickly made a name for himself as somewhat of a classy utility back usually playing at either fullback or filling one of the half positions.

Lennon missed the majority of the 2003 season because of injury, mainly due to a broken leg which meant he could only make a few appearances for the club that year and at the conclusion of the 2004 he moved to Manly-Warringah Sea Eagles.

[4] Lennon was originally signed as a depth replacement on an incentive-based offer for the beginning of the 2004 National Rugby League season and was seen as the long term option to take over from Luke Dorn who had been released from the club because of his arrival.

After newly promoted Hull Kingston Rovers had sustained several injuries to key players during their maiden Super League season, head coach Justin Morgan (a Wales teammate) offered Lennon a one-year deal at Craven Park.

[9] For the following five years Lennon would go on to make a further eight appearances for Wales with matches against Australia and New Zealand[10] as well as playing in the European Nations Cup where he scored a sixteen-point haul against Russia at Aberavon in 2003.

Lennon won caps for Wales while at the Castleford Tigers, the Manly Sea Eagles, the Hull Kingston Rovers, and the Celtic Crusaders 2001...present 13(10, 12?