This very idea of “signalling” suggests that the association between skills and formal qualification might be central to how skills are rewarded on the labour market. Less-educated adults are experiencing great difficulties on today’s labour markets across all advanced economies (Abrassart, 2013, Gesthuizen, Solga and KUnster, 2011, OECD, 2016). They face higher risks of unemployment than their better-educated counterparts. When they do find employment, it tends to be in low-status occupations characterised by meagre wages and low job security. Hence, improving the labour market prospects of less-educated adults is a prime challenge for countries that want to maintain social cohesion and avoid excessive social inequalities.