The study of organic ferroelectrics based on mixed-stack charge-transfer salts is currently a rapidly developing research field. These materials attract interest as highly tailorable ferroelectrics whose dielectric properties include a strong contribution from an electronic charge transfer mechanism that operates alongside the more conventional ionic displacement mechanism. The prototype for this type of system is TTF-CA which combines the electron donor molecule TTF with the electron acceptor molecule p-chloranil (CA). The ferroelectric transition is at Tc=81 K and is accompanied by a neutral-ionic transition and a dimerisation of the chain. Our ongoing muon studies have revealed a wealth of information on this system and have identified a hidden magnetic character to this ferroelectric transition, consistent with previous predictions of it having an underlying multiferroic nature.