A former chief executive of Marks & Spencer has been named as a government adviser on employment, marking the latest effort to confront the escalating crisis of youth unemployment. Marc Bolland, who led the high street retailer between 2010 and 2016, is set to chair a summit bringing together senior business figures, as concerns grow that the UK could face a “lost generation” without swift and decisive action. Roughly 1 million young people aged 16 to 24 — around one in eight — are