A gauge-invariant quantisation of chiral QED in four dimensions is considered. By the allowance of an appropriate gauge-invariant action beside the symmetry-restoring Wess-Zumino action, the theory is shown to be renormalisable. Also as a result, several new gauge-invariant couplings, which conform with a discrete CP symmetry, are generated. Among them are a four-point interaction and a mass term for the vector bosons. The difference between this mass and the one generated by the Higgs mechanism is then discussed.