Boris Johnson loses another deputy mayor

Tim Parker stood down as chief of staff when Mr Johnson stripped him of his role of running Transport for London from next month.

Mr Parker is the second of Mr Johnson's deputies to leave since May and the third senior aide to go. Deputy mayor Ray Lewis was forced to stand down after wrongly claiming he was a magistrate and senior political strategist James McGrath quit over a race row. The appointment of Mr Parker, 52, one of the City's most successful private equity businessmen, was seen as a major coup for the new City Hall administration. He was brought in with a brief to restructure the Greater London Authority and was expected to do the same with TfL's £6.5 billion budget. But the Mayor said he was taking personal charge of TfL, which he said was "absolutely crucial" to doing his job effectively. He said the nature of the decisions TfL made were "too political" for an unelected aide to preside over.

It meant there was no role for Mr Parker, the man branded "The Prince of Darkness" for his ruthless cost-cutting in business, including such firms as the AA and Kwik-Fit.

Mr Johnson has appointed six deputy mayors with various responsibilities since his election but Mr Parker's title was First Deputy Mayor. The departure of City Hall's chief of staff after two months in the job will raise questions about Mr Johnson's judgment and represents a major policy U-turn.

Mr Johnson initially took the chair of the body, saying it was an interim measure - but today announced his change of mind. Ken Livingstone chaired TfL throughout his two terms as Mayor.

Mr Parker's departure will be felt keenly as he brought with him wide-ranging corporate experience and an eye for financial detail many feel Mr Johnson lacks.

Both men insisted the parting was amicable and said Mr Parker, who was paid a £1 nominal salary, would retain a seat on the TfL board and act as an unofficial adviser to the Mayor on transport and business issues.

Mr Johnson said: "Over the last few weeks it has become increasingly apparent to both of us that the nature of the decisions that need to be taken are highly political, and there is no substitute for me, as the directly elected Mayor, being in charge. There are limits, therefore, to what can be delegated."

Mr Parker said: "I have concluded that it would not be appropriate for an unelected official to chair a body which is responsible for most of the money and a large part of the brief of an elected Mayor. I also agree with the Mayor that my position as adviser does not justify my full time and exclusive commitment to the GLA or the title of First Deputy Mayor. We have therefore decided to adjust the management structure and abolish that post."

He told the Standard: "I'm obviously disappointed but also realistic. It's something I hadn't envisaged but I think it's the right thing to do." He denied the decision to let him go reflected badly on the Mayor. "We tend to make a big song and dance about these things in the public sector but in the private sector it's not unusual to change the organisational structure. It's better to do it sooner rather than later," he said.