Is mentoring black teenagers an issue of colour?
Boris has brought back a former deputy mayor, who quit amid claims of financial irregularities and inappropriate behaviour.
Ray Lewis has always denied the allegations.
But today Mr Lewis was reintroduced as an adviser.
He'll be helping to run a new mentoring project that will target the attitudes and behaviour of troubled teenagers.
The aim of the scheme, which launches in the Autumn, is to recruit 1,000 adult males to act as mentors.
We're told he and Richard Taylor, who's the father of murdered schoolboy Damilola, will both be volunteering their "time for free" to ensure the plans work.
Boris Johnson said:
"There is no magic solution to ending youth crime, but I am more determined than ever to use this new partnership to turn around the lives of as many troubled young people as possible".
And those young people are disproportionately young black men. They are the most affected by serious violent crime here in the capital.
The figures show that 77% of teenage murder victims from 2007 to 2009 were black. And more than two thirds of young offenders serving life sentences in London were black.
The Mayor's press office says most of the mentors on the new scheme will be black.
Yet does the colour of your skin matter?
It's a question David McQueen asks in his blog.
He says he's worked at Ray Lewis' Eastside Young Leaders Academy in Newham.
"I think we in the Afro community miss a big trick when we think that only black men are the only ones to mentor black boys," says David, who has worked with young people for 20 years.
"There is a certain dynamic that comes from male mentorship but I think we should widen the pool to include any man capable of good leadership."
Today also saw the launch of another mentoring scheme called "Grandmentors" designed to help "troubled teens."
The three year pilot project, which is run by the charity Community Service Volunteers, is based in Islington and Hackney. It's open to anyone aged over 50, who wants to "transform the lives of youngsters."
So what makes a good mentor?
Does it matter how old you are, whether you're male or female, or white, Asian or black?