Comparison of the ages of the hot companions (abscissa) and the RSG components (ordinate) of the 16 binary systems studied. The dashed grey line shows the expectation of coevality, i.e. a one-to-one relationship. The ages of the two components are inconsistent in seven of the 16 cases at the ∼3σ level. These sources are marked with red stars. The black point on the left indicates the typical uncertainties.