Symons has had an interesting route to the top. He started out in the Saracens youth system before leaving to pursue a career in rowing. An injury to his forearm ended his rowing career and saw him make a return to rugby. In 2011, he started playing professionally for Esher for whom he made 14 appearances.
2012 saw him head south to New Zealand where he set up base in Christchurch and initially saw action for the Canterbury B side and Crusaders Knights development team before being named in the Canterbury squad for the 2013 ITM Cup. He became a regular starter in his first full season and earned himself a Super Rugby contract with two-time champions the Chiefs for the 2014 Super Rugby season.
On 25 March 2015, Symons returned to his home nation to sign for London Irish in the Aviva Premiership from the 2015-16 season following Chiefs assistant coach Tom Coventry to the English side. He was named their Player of the Season in 2016.
One of a very select group of English players to experience Super Rugby (courtesy of a season in New Zealand with the Chiefs) Symons went on make 26 appearances for the Club across all competitions in his first campaign, and has played a vital role in improving the team's operations at set piece.
Symons joined Harlequins for the 2018/19 season from Wasps and quickly established himself as a crucial figure in the squad, thanks to his consistency of performance and his natural leadership qualities.