The loss of James McGrath will be a major blow to Boris Johnson.
Not only did the canny Australian strategist play a central role in his election campaign but he also provided the Mayor with a crucial link to Conservative Central Office once he came to power.
Mr McGrath, 34, had worked for the Tories for seven years and is credited by several senior figures for helping to turn the party round nationally. He was described by shadow cabinet office minister Francis Maude, for whom he worked as chief of staff, as "one of our real big hitters".
The strategist, who was number two to Lynton Crosby, had been expected to spend the next two years devising Boris's political strategy and then return to Tory headquarters to help the party win the next general election. That option has also now been ruled out.
Whether McGrath decides to take his own advice and go home or not, the Mayor is left with a big hole in his team.
