The real and imaginary parts of the optical transmittance and the relative permittivity have been measured for a polysiloxane ferroelectric liquid crystal polymer (FLCP) subjected to a weak alternating electric field. A simple dynamical model of the collective switching has been adopted for describing the director motion and the transport of ions through a FLCP cell. Numerical solution of a set of equations governing the director dynamics allows us to explain the transmittance and dielectric response of a FLCP cell. The model is shown to reproduce the experimental dielectric and optical transmittance response quite satisfactorily.