Terzan 10: upper panels: Gaia DR2 proper motions for the stars in common between the HST catalogue and Gaia DR2; magenta dots are the stars located within 15 arcsec from the cluster centre that also have a proper motion < 2 mas yr⁻¹ from the mean motion of the cluster (i.e. −6.96, −2.45 mas yr⁻¹). Bottom panels: m_F606W vs. m_F606W−m_F160W CMD before (left-hand panel) and after (right-hand panel) the differential-reddening correction. Grey points are all the stars in the HST catalogue; black points are the stars in the HST catalogue that are located within 15 arcsec from the cluster centre; magenta points are the stars in common with Gaia DR2 catalogue that are located within 15 arcsec from the cluster centre and have a proper motion < 2 mas yr⁻¹ from the mean motion of the cluster.