Primarily a prop, he captained New Zealand and played for the Canberra Raiders, North Queensland Cowboys and Melbourne Storm.
In 1989, Lomax, alongside his three brothers (Arnold, Tony and David), played for Wainuiomata in their Wellington Rugby League Grand Final win over Upper Hutt.
At the end of the year, he was selected to go on the 1993 New Zealand rugby league tour of Great Britain and France, playing in all five test matches.
In 1994, Lomax played 23 games for the Raiders and won the club's Player of the Year award but missed their Grand Final win over the Canterbury-Bankstown Bulldogs due to suspension.
A week earlier, he was sent off and charged for a high shot on Billy Moore in the side's 22–9 preliminary final win over the North Sydney Bears.
Following the incident, a routine scan discovered that Ritson had a life-threatening brain cyst, from which he would never fully recover, ending his career.
[15] He is believed to have received a large payout from the Australian Federal police for wrongful arrest [16] In 2012, he was named at prop in the Wellington Rugby League's Team of the Century.