His speech, to the Centre for Policy Studies in London, is a bid to trump Tony Blair who yesterday reaffirmed his commitment to shaking up the youth justice system. In his speech, Mr Letwin says: " Academic research on both sides of the Atlantic has grown to support the evidence that the seeds of future offending are sown in infancy. The evidence also shows that the single most important ingredient in a young child's life is the quality of his or her parenting.