We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey .
This is the first extensive study of this cluster from high resolution spectroscopy .
We derive abundances of O , Na , Mg , Al , Si , Ca , Sc , Ti , Fe , Cr , Ni , Y , Ba , and La .
We find a metallicity of [ Fe/H ] = -2.19 \pm 0.03 and find no evidence for a metallicity spread .
This metallicity makes NGC 4372 one of the most metal-poor galactic globular clusters .
We also find an \alpha -enhancement typical of halo globular clusters at this metallicity .
Significant spreads are observed in the abundances of light elements .
In particular we find a Na-O anti-correlation .
Abundances of O are relatively high compared with other globular clusters .
This could indicate that NGC 4372 was formed in an environment with high O for its metallicity .
A Mg-Al spread is also present which spans a range of more than 0.5 dex in Al abundances .
Na is correlated with Al and Mg abundances at a lower significance level .
This pattern suggests that the Mg-Al burning cycle is active .
This behavior can also be seen in giant stars of other massive , metal-poor clusters .
A relation between light and heavy s- process elements has been identified .