Chappell will join the rival publishing company Square One as an equity partner. Square One has clients including Direct Line, Thames Water and Lloyds TSB.
After helping to merge Citrus Publishing, the company that he was the managing director of, with John Brown in April 2002, Chappell moved to the US to help build the company's international client base.
Square One, which Chappell joins on 1 December, was launched in 1992 by its founding directors, Sean King and Peter Dean.
Chappell's task at Square One is to develop further the company's offer to help clients to get greater value from their publications.
Chappell said that a key reason for moving from John Brown, where he helped it win the US accounts for clients such as Bloomingdales, Nestle and the US military magazine Drill, was to work for a smaller, more flexible operation. "Large agencies are not always affordable and their size can make it difficult for them to deliver consistent personal service," he said.
King said: "Simon's track record of success makes him an ideal addition to the team here. We believe that we have the opportunity to become a top-five player in the contract publishing sector within the next five years."