Fit results of a Gaussian mixture with 30 components to the redshift distribution in five tomographic redshift bins. Blue curves indicate redshift distributions fitted to the pre-calibrated DIR redshift histograms, shown in black. Shaded regions indicate the uncertainties on the redshift distributions derived from the diagonal elements of the correlation matrix of fit parameters, shown in Fig. 3. Orange curves represent the redshift distributions after iterative optimisation of cosmological and nuisance parameters.