Boris Johnson began the hunt yesterday for a new political strategist, saying that he was "keen to move on and focus on the task ahead" in light of the race furore that has enveloped City Hall.

Mr Johnson denied accusations by the Labour group in the London Assembly that he had dithered when taking action against James McGrath, his senior adviser who said that Caribbean blacks could go home if they did not like it in London.

Mr Johnson's spokesman told Times Online that the Mayor of London wanted to receive sound advice and make sure he had all the facts before he made his decision.

The spokesman said "Mr Johnson was not going to get rid of a deeply loyal man who is not a racist without hearing his side of the story. He's not going to sack someone in a mad race like that when it's not even in the public domain. We have got to go through a patient process." The spokesman said Mr Johnson is now looking for the "best person or persons out there" to try to fill the gap left by Mr McGrath

The Labour group in the London Assembly had questioned why it took Mr Johnson the weekend to decide that Mr McGrath should resign after his remarks were aired on a website on Friday.

A spokesman for the Labour group said that Mr Johnson's natural inclination was to blame the journalist involved rather than to take decisive action. Although Mr Johnson forced Mr McGrath to resign, the Mayor of London still claims the comments were taken out of context.

The Labour spokesman said: "Given the sensitivity with which some of his previous comments have been received, Boris should be going out of his way to make it clear that people of all ethnic backgrounds are welcome here, not waiting to be told whether these offensive views were aired in the right context. In what context is it acceptable to tell Caribbean people to go home if they don't like their Mayor?"

The furore came after Mr Johnson raised the hackles of equality campaigners last week for dropping the central anti-racism message of the Rise festival. He has been criticised in the past for calling black children “piccaninnies” and saying that black people had “water melon smiles”.

Mr McGrath made the remarks when questioned about the suggestion that Mr Johnson’s win could result in the departure of many older Caribbean immigrants from the capital. According to Marc Wadsworth, the anti-racism campaigner writing on the internet news site www.the-latest.com, Mr McGrath replied: “Well, let them go if they don’t like it here.”

Late yesterday afternoon there was no indication that Mr McGrath’s position was under threat. However, Mr Johnson’s action, a few hours later, highlights the mayor’s sensitivity over race. The Times understands that he was also motivated in part by an intention to show distinct differences between his administration and that of his predecessor, Ken Livingstone.

Mr Johnson said last night that there was a need for “crystal clarity” on the issue of race.

“James is not a racist. He shares my passionate belief that racism is vile, repulsive and has no place in modern Britain. But his response to a silly and hostile suggestion, put to him by Marc Wadsworth, allowed doubts to be raised about that commitment,” he said.

Mr Wadsworth said that he was shocked by Mr Johnson’s swift reaction as he “didn’t want to make a big fuss”. However, he said it was the right decision as the remarks were “insensitive at the very least”.

David Cameron, the Tory leader, who has worked with Mr McGrath in the past and was consulted over the decision, said today that while he did not think he was a racist, it was a "lapse in judgment".

“It was regrettable, it was something he shouldn’t have said.”

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