Top:difference in log t between the ages found in this study and those quoted in the MWSC catalogue. The dashed line indicates the mean value. Middle: Difference between the [Fe/H] found in this study and those quoted in the MWSC catalogue (for the OCs with metallicity estimates). The dashed blue line indicates the mean value. Bottom: metallicity ([Fe/H]) obtained in this study based on JHK_S photometry, against Galactocentric radius. The red cross indicates the solar metallicity and Galactocentric radius (8.34 kpc, Reid et al. 2014).