This letter appears in today's Guardian:

Before the BBC goes too far down the road of selecting the successor to Mark Thompson as director general (Profile, 26 March), it should pause and ask if the job is correctly configured. Despite Thompson's record, it has long been clear that to ask one person to direct and manage both the BBC's entire creative side and its increasingly complex digital and technical side is expecting too much. If the DG's job was more precisely defined as having prime responsibility for the BBC's programming and creative output, this would leave a redefined chief operating officer to direct the BBC's involvement in the whole digital world. This might enhance clarity of role and function and improve the BBC's effectiveness.
John Tusa
Managing director, BBC World Service, 1986-92