Toroidal field coil current measurements presently available at the JET tokamak (Hall probe, Shunt, Rogowski coil and an optical fibre measurement) were investigated over 8 years (2008-2014) in order to explain the radial discrepancy between various electron density and temperature profiles focusing on reflectometry and the electron cyclotron emission (ECE) diagnostics. A 1.21­1.8% difference is found between the optical fibre measurement and the reference magnetic coil current based on the Rogowski measurements that reduces the radial discrepancy by at least a factor of two between diagnostics. Dedicated pulses in different power supply configurations indicate a static current is flowing in the toroidal field circuit (not measured by the Rogowski coils) that can be a result of an interplay between the flywheel generator converter and the static units supplying power to the toroidal field