  We construct the three point function involving an axial vector current and
two energy-momentum tensors for four dimensional conformal field theories.
Conformal symmetry determines the form of this three point function uniquely up
to a constant factor if the necessary conservation conditions are imposed. The
gravitational axial anomaly present on a curved space background leads to a
non-zero contribution for the divergence of the axial current in this three
point function even on flat space. Using techniques related to differential
regularisation which guarantee that the energy-momentum tensor is conserved and
traceless, we calculate the anomaly in the three point function directly. In
this way we relate the overall coefficient of the three point function to the
scale of the gravitational axial anomaly. We check our results by applying them
to the examples of the fermion and photon axial currents.
