Cambridge RUFC joined the newly formed league structure in 1988 and by 1991 was playing in London 3 North East. After five years in this division, the club was promoted to London 2 North and after four years in this division, was promoted at the end of the 1998–99 season to London 1, which feeds into the National Leagues. In the Club's first season in London 1, they achieved 4th place, plus a run to the semi-final of the NPI Cup, falling just one match from Twickenham, after defeat away at Hull by 21–17. London 1 status was secured again for the 2001–02 Season, but the squad led to relegation at the end of that season. However, by the end of the 2003–04 season, a rebuilt side regained promotion to London 1. Cambridge also won the Eastern Counties Cup for the first time and regained the Cambridgeshire Cup from perennial rivals Shelford. This time, the stay in London 1 was to be even shorter; At the end of an exciting season the League championship lay between Worthing and Cambridge at the start of the final round of matches: Worthing at home to Canterbury and Cambridge at home to Basingstoke. The championship would go to the team achieving the greatest points difference. In the event, Cambridge won by 96–15 and Worthing were condemned to the play-offs. Cambridge went on to beat Norwich in the Eastern Counties Cup Final and Shelford in the Cambridgeshire Cup Final — the second successive treble, and promotion to National League rugby for the first time.