Former McDonald's sponsorship lead signs for sports management agency ISC
Marks' arrival is a further boost to ISC, who manage the career of England rugby's rising star Joe Cokanasiga as well as Olympic weightlifter Zoe Smith and gymnast Dom Cunningham.
He has a wealth of governance experience as participation Director at the LTA and the RFU and ISC Managing Director Nick Robinson said: "We are excited to bring in someone of Alastair's experience to our team, which amplifies our ability to merge great athlete representation with world class commercial exploitation.
"Alastair is also a man of great values which is something that ISC's success is built on and his arrival enables us to manage athletes from their first contract to the end of their sporting careers."
Marks added: "I am delighted to be joining Nick and his talented team at ISC and look forward to building on its previous commercial successes.
"With a strong all-round offer built around a high-profile athlete talent base, driving revenue for federations and NGBs as well as building strong partnerships with brands and athletes we are uniquely placed to help our partners go from strength to strength."
ISC also represents Premiership footballers such as Sofiane Boufal (Southampton)
ISC's Commercial Division has counted National Governing Bodies British Weightlifting and England Handball as retained clients.