David Sharrock will assume the role of chief operating officer worldwide, and will sit on the board along with founding directors Carl Halliday, Nigel Bale, Chris Gosling and Tim Elliott.
Wallace joined the company when it was created in 2007 and as part of his departure, he will leave his positions as a director and executive of the WRG Worldwide board and its associated subsidiaries.
Jim Faulds, non-executive chairman at WRG, said the team is now focused on overseas growth in North America and Asia, with plans to launch an agency in China.
He added: "The future is very bright for WRG group. Following our successful entry into the Hong Kong market, plans are now underway to launch an agency in China. We continue to expand our offering to meet client demand whichis paying dividends, with our healthcare division in particular performing ahead of expectation."
Speaking of his departure, Wallace said: "I am very proud of the WRG team and what we together have created. I wish the staff and directors great success in the future."
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