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Using two epochs of HST/WFPC2 images of the metal-rich globular cluster NGC6528 we derive the proper motions of the stars and use them to separate thestars belonging to NGC 6528 from those of the Galactic bulge. The stellarsequences in theresulting colour-magnitude diagram for the cluster aresignificantly better determined than in previously published data. Fromcomparison of the colour-magnitude diagram with the fiducial line for NGC 6553from Zoccali et al. (2001) we conclude that the two globular clusters have thesame age. Further, using alpha-enhanced stellar isochrones, NGC 6528 is foundto have an age of 11+-2 Gyr. This fitting of isochrones also give that thecluster is 7.2 kpc away from us. From the measured velocities both the propermotion of the cluster and the velocity dispersion in the Galactic bulge arefound. NGC 6528 is found to have a proper motion relative to the Galactic bulgeof mu_l=0.006 and mu_b=0.044 arcsec per century. Using stars with 14<V_555<19(i.e. the red giant branch and horizontal branch) we find, for the Galacticbulge, sigma_l= 0.33+-0.03 and sigma_{b}= 0.25+-0.02 arcsec per century. Thisgive sigma_l/sigma_b=1.32+-0.16, consistent both with previous proper motionstudies of K giants in the Galactic bulge as well as with predictions by modelsof the kinematics of bulge stars.Comment: 19 pages, Latex, A&A macro included, 3 ascii tables included (to be  published electronically in the journal) . A&A in pres

A new, cleaner colour-magnitude diagram for the metal-rich globular cluster NGC 6528