Hess diagrams of the fields on the north-west side of the SMC. Each subpanel contains about 60 000 stars, and they are ordered according to their distance from the SMC centre. Two isochrones (t = 1 Gyr; Z = 0.001 dex, solid line and t = 10 Gyr, Z = 0.001 dex, dashed line), corrected for the distance modulus of the SMC, are superposed as a comparison. At the top of each subplot the range of distances from the SMC centre is indicated.