Threshold behaviour in gauge boson pair production at LEP 2

We discuss the form of the amplitude for gauge boson pair production at or near threshold. We show that in the case of W-pair production at LEP2 near threshold only one anomalous electromagnetic coupling can contribute. This anomalous coupling is CP violating and contributes to the electric dipole moment of the W. Since this coupling is likely to be small, it is important to look for ZZγ couplings in Zγ production. These couplings are not suppressed at the W threshold.