In the present work we apply the neutral beam modulation technique to a set of JET discharges in order to obtain information on the radial transport of the toroidal angular momentum. This perturbative technique has been often used for heat transport in the past; it is particularly suited to separate possible pinch terms from the momentum diffusivity, otherwise impossible to decouple with a steady-state momentum balance analysis alone. In this paper a model based on the Ion Temperature Gradient (ITG) turbulence, which consists of a constant Prandtl number of the order unity combined with an inward pinch, is validated against data from the JET experiment. The machine size and the good space and time resolution of the Charge Exchange system make JET particularly suitable for this study. Sensitivity studies assess the accuracy range of our predictive modelling.