Waltham Forest has appointed Joe Derrett as head of media and external relations.
His departure creates the first vacancy in the London Mayor's press team since Guto Harri was appointed as director of communications in 2008. Derrett reports to chief press officer Samantha Hart.
Derrett has worked in the press office since August 2006, before which he was head of the London Labour Party's press office. He takes up his new role in September.
Last year, the blogger Guido Fawkes suggested former Labour press officer Derrett would not be 'in tune with the new order at City Hall for long' after the appointment of Johnson.
The role of the Mayor's deputy chief press officer has been advertised as being paid between £44,214 and £47,860.
Waltham Forest has 23 people in its corporate comms team. In March, Waltham Forest undertook a review of its comms strategy to bring it in line with the council's sustainable community strategy.