James joins from Bacardi Global Brands to become vice president of client services alongside Fiona Lloyd who is promoted from Carat Global Management to the role of vice president of programme management.
The third member of the new client services line-up is Samuel Tait who is named new business director. Tait was most recently director of digital at another Aegis agency, Act Europe.
The three hires follow on from the appointment of Niku Banaie, vice president of strategy and innovation, and Jamie Edwards, vice president of client services. All will report to David Pullan, who was appointed president of Isobar Global Client Management in March of this year.
Pullan said: "Our international team is now world-class, matching our network agencies. We are ahead of the game in developing programme management as a specialist discipline in its own right; we are putting digital thinking right at the top of our clients' agendas; we are integrated in our strategies; and we are significantly boosting the effectiveness of our specialist campaign execution."
Nigel Morris, CEO, Isobar, said: "This is a key moment in the marketing communications sector. We have championed the role of digital for the past five years. We have invested in Isobar to become the largest global digital network with a trajectory that has seen it double in the last 15 months.
"We have ground-breaking expertise with a diverse and truly global reach. Now, the investment in such outstanding global talent means that we can provide clients with the best strategic advice as well as the most innovative specialist capabilities."
The client management team focuses on planning and managing the execution of digital services across multiple markets for Isobar's international clients.
The team, based in London, the US, France, Germany and Hong Kong will oversee the international clients of sister agencies Carat and Vizeum, as well as Isobar's own international specialist digital-only client base.