He made his full debut for Saracens in 2007-08 season against Bristol in the EDF Energy Cup. A regular in the team in the 2010/11 title winning season, a leg injury picked up in the final prevented him from joining up with England Saxons that summer. Saull made his 100th appearance for Saracens on 27 December 2011, after replacing the injured Jacques Burger in the squad.
On 18 April 2013, Newcastle Falcons signed Saull to a two-year contract from the 2013-14 season. On 17 April 2015, Saull signs for Yorkshire Carnegie, competing in the RFU Championship on a two-year contract from the 2015-16 season.