  We present an analysis of high-resolution FLAMES spectra of approximately 50
early B-type stars in three young clusters at different metallicities, NGC6611
in the Galaxy, N11 in the Large Magellanic Cloud (LMC) and NGC346 in the Small
Magellanic Cloud (SMC). Using the TLUSTY non-LTE model atmospheres code,
atmospheric parameters and photospheric abundances (C, N, O, Mg and Si) of each
star have been determined. These results represent a significant improvement on
the number of Magellanic Cloud B-type stars with detailed and homogeneous
estimates of their atmospheric parameters and chemical compositions. The
relationships between effective temperature and spectral type are discussed for
all three metallicity regimes, with the effective temperature for a given
spectral type increasing as one moves to a lower metallicity regime.
Additionally the difficulties in estimating the microturbulent velocity and the
anomalous values obtained, particularly in the lowest metallicity regime, are
discussed. Our chemical composition estimates are compared with previous
studies, both stellar and interstellar with, in general, encouraging agreement
being found. Abundances in the Magellanic Clouds relative to the Galaxy are
discussed and we also present our best estimates of the base-line chemical
composition of the LMC and SMC as derived from B-type stars. Additionally we
discuss the use of nitrogen as a probe of the evolutionary history of stars,
investigating the roles of rotational mixing, mass-loss, blue loops and
binarity on the observed nitrogen abundances and making comparisons with
stellar evolutionary models where possible.
