In the field of flexible displays there is a need for an electro-optic filament that is capable of being woven, knitted or crocheted. An electro-optic filament or fibre (10) includes an elongate core (11) extending lengthwise within a volume (12) of polarisable material; and an outer electrode member (13) overlying the volume (12). The core (11) and outer member (13) are electrically conducting and connectable to electrical potentials to generate a radial field in the polarisable material. The outer member (13) is optically transmissive and/or transflective. The polarisable material (12) exhibits an optical effect such as a colour change, change in polarisation or change in reflectivity, when subjected to a said field or a change in a said field. The filament or fibre may readily be woven into eg. a fabric or a garment, using conventional textile processing machinery.