  We present stellar metallicity measurements of more than 600 late-type stars
in the central 10 pc of the Galactic centre. Together with our previously
published KMOS data, this data set allows us to investigate, for the first
time, spatial variations of the nuclear star cluster's metallicity
distribution. Using the integral-field spectrograph KMOS (VLT) we observed
almost half of the area enclosed by the nuclear star cluster's effective
radius. We extract spectra at medium spectral resolution, and apply full
spectral fitting utilising the PHOENIX library of synthetic stellar spectra.
The stellar metallicities range from [M/H]=-1.25 dex to [M/H]> +0.3 dex, with
most of the stars having super-solar metallicity. We are able to measure an
anisotropy of the stellar metallicity distribution. In the Galactic North, the
portion of sub-solar metallicity stars with [M/H]<0.0 dex is more than twice as
high as in the Galactic South. One possible explanation for different fractions
of sub-solar metallicity stars in different parts of the cluster is a recent
merger event. We propose to test this hypothesis with high-resolution
spectroscopy, and by combining the metallicity information with kinematic data.
