A network restructure will see Adrian Holmes add the title of network chairman to his current role as the worldwide chief creative officer.
He said: "I will begin by doing both jobs and seeing how it goes. But I suspect it will be too much for one person and that we will have need of a global creative director."
However, Holmes insisted the group had not got as far as considering candidates.
A new global creative chief would be tasked with upholding and raising creative standards at Lowe offices in more than 90 countries.
The extended role for Holmes is part of a revamp to sustain the group's relationships with clients to whom Lowe was close, notably Tesco and Unilever.
Holmes has had a long-standing involvement with Tesco. Terry Rosenquist, the worldwide client services director with responsibility for the Unilever business, has been named vice-chairman.
Simon Clift, Unilever's president of marketing for Home and Personal Care, said: "For some time now, Sir Frank has not been directly involved in our business, so I expect his departure to have little impact for us. I am confident that the management team - that Frank himself put in place - will continue to inspire the agency to the same high standards that he did."
Lowe's career, p4; London rejig, p16; Perspective, p25.