The information provided by different diagnostics has been combined in order to characterize the fast electron distribution function in Lower Hybrid Current Drive experiments on JET. In particular X-ray and electron cyclotron emission data are complementary in defining the fast electron energy content in the directions parallel and perpendicular to the magnetic field A numerical analysis chain has been developed which identifies the main moments of the distribution function of the current carrying fast electrons and allows simulations based on these moments to be compared with X-ray emission, electron cyclotron emission and magnetic data. The method of analysis and the associated diagnostics are described, and results are presented which have been obtained during the Lower Hybrid Current Drive campaign on JET.