  We present a calculation of the leading order hadronic contribution to the
anomalous magnetic moment of the muon for a dynamical simulation of 2+1 flavour
QCD using domain wall fermions. The electromagnetic 2-point function is
evaluated on the RBC-UKQCD lattice gauge configurations and this is fitted to a
continuous form motivated by models of vector dominance. We determine a robust
and reliable technique for performing this fit, allowing us to extract the most
accurate results possible from our ensembles. This combined with data at very
light quark masses produces the result a_\mu^{(2)had}=641(33)(32) x 10^{-10} at
the physical point, where the first uncertainty is statistical, and the second
is an estimate of systematics, which is in agreement with previous results. We
outline various methods by which this calculation can and will be improved in
order to compete with the accuracy of alternative techniques of deducing this
quantity from experimental scattering data.
