  We derive a new age for the Gamma^2 Velorum binary by comparing recent
observations to our set of binary models. We find that it is very unlikely the
stars have not interacted, which implies that previous estimates of the age
from single-star models of 3.5+/-0.4 Myrs are incorrect. We prefer an older age
of 5.5+/-1 Myrs that agrees with the age of other lower mass stars in the Vela
OB association. We also find that our favoured binary model shows the
components of the binary have interacted in a Case B, post main-sequence,
mass-transfer event. During the mass-transfer event, the envelopes of both
components where radiative and therefore the damping of tidal forces are
relatively weak. This explains why the binary is still eccentric after
mass-transfer.
