Following his coaching stint at Manly, Arthurson became the club's secretary, taking over from Jack Munro after Munro's passing in 1963. Arthurson held this post for 20 years, during which time he helped build the Sea Eagles into one of the most successful clubs in the league by use of his negotiating skills and the club's finances, something which made Manly the team others loved to hate (many believe that Arthurson's only rival as a top club administrator in Australia was his close friend, Canterbury-Bankstown's Peter "Bullfrog" Moore). During his time as club secretary, Arko signed players who went on to become legends not only at Manly but also in rugby league. His list of players includes Graham Eadie, Ken Irvine, Terry Randall, Mal Reilly, John O'Neill, Ray Branighan, Max Krilich, Phil Lowe, Paul Vautin, Les Boyd, Kerry Boustead, and possibly his greatest signing, Australian Rugby League Immortal Bob Fulton.