Harry Fletcher, from the National Association of Probation Officers, said the idea of mentors was "excellent" but he thought it would never happen because of the sheer numbers needed to make it work. He told the BBC:
You'd need an army of volunteers or employees of private companies to do it properly.
More top news
It'll become increasing cloudy tonight, with outbreaks of rain in the northwest
Six months on from the referendum, Political Editor Robert Peston takes a road trip to find out what people feel about Brexit now.
Donald Trump has been criticised for appointing a man who once sued the Environmental Protection Agency to be its new boss.