James joins Starcom from Aegis Media, where he was the global vice-president of client services and worked on digital strategy for clients including Johnson & Johnson, Nokia and Disney.
In his new role, James, who before joining Aegis was the global head of digital at Bacardi Global Brands, will be responsible for Starcom MediaVest Group's digital offering across the region and provide digital direction across both the Starcom and MediaVest client portfolios.
The appointment comes as Bannerman, the chief client officer, prepares to leave the agency on 1 April to join the Australia-based, out-of-home media owner EYE as its global marketing director.
Bannerman had moved to the chief client officer role last October following the appointment of Matt James, the former managing director of OMD International and Manning Gottlieb OMD, as the managing director of Starcom in the UK.
Stewart Easterbrook, the group chief executive of Starcom MediaVest, said that the agency would consider recruiting for the chief client officer role in time, but that as the role was "created around Alastair's skills", it would not be filled immediately.