In a letter forwarded to staff from Nick Brien, chief executive of Universal McCann, Dudgeon had these parting words to say to his staff: "I have thoroughly enjoyed working with Nick to shape the new Universal McCann and feel that all the right pieces are in place now to fuel Universal McCann's future growth and success.
"However, with that job complete, I want to get back to spending my time dealing with the real issues facing both clients and media owners rather than dealing with operational issues. I feel now is the right time to move on."
The network said his departure was by "mutual agreement".
Dudgeon has been with the agency for more than 25 years and has held senior posts in London and New York at Universal MCann. He was previously Universal McCann's executive vice-president and worldwide operations director. Up until 1997 he was European media director.
Brien said: "Murray has filled a number of critical roles for Universal McCann, both in New York and London, most recently as worldwide COO. He has made a significant contribution to Universal McCann, our clients and our people but feels that now is the right time to re-focus his energies in a new direction.
"I shall be sorry to see him leave but I am happy that we will still have access to his knowledge and experience in a consultancy role going forward, as he will continue to work with the company on a number of special projects."
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