We present colour-magnitude diagrams for two rich (~10^4 Msun) Large
Magellanic Cloud star clusters with ages ~10^7 years, constructed from optical
and near-infrared data obtained with the Hubble Space Telescope. These data are
part of an HST project to study LMC clusters with a range of ages. In this
paper we investigate the massive star content of the young clusters, and
determine the cluster ages and metallicities, paying particular attention to Be
star and blue straggler populations and evidence of age spreads. We compare our
data to detailed stellar population simulations to investigate the turn-off
structure of ~25 Myr stellar systems, highlighting the complexity of the blue
straggler phenomenon.Comment: 15 pages, accepted for publication in MNRAS, postscript version with
higher quality figures available from
http://www.ast.cam.ac.uk/~raj/biblio.htm
