Britain has lagged behind the G7 countries in labour productivity in recent years. There is also an emerging concern about a potential post-Brexit skills deficit. Upskilling the existing workforce via on-the-job training may be a vital policy tool available. Using a panel of organisations and their 'Investors in People' accreditation status, this paper empirically examines if accreditation promotes upskilling. Fixed effects estimates reveal that accreditation enhances on-the-job training but only in private sector organisations. Difference-in-differences estimates using unaccredited and di-accredited organisations as alternative matched comparators reinforce the FE findings. Policy may have to further engender accreditation schemes that boost worker upskilling to address the productivity concerns and to cope with the rapid technological changes better.