Errie is the brother of Toulon player Michael Claassens who plays at scrum half and has represented the Free State Cheetahs and the Springboks.
Claassens moved to the UK in 2005 to sign for the Rotherham Titans where he spent four seasons, developing from a bit part player into a proven try scorer.
In 2009 he moved to London Welsh where he was to further his reputation with a strong try scoring record and a number of sparkling individual performances.
Claassens was named as part of the Rugby Times magazine 2009/2010 RFU Championship "Dream Team" thanks to his consistently strong play and try scoring reputation.
However, on 21 May 2014, he left Bristol by mutual consent[2] as he officially joined London Scottish on a two-year contract.