Described herein is a luminaire controller (6) which is mountable within a luminaire head by means of fastening areas (33) provided in a wall (34) forming part of an upper housing part (32) and/or a baseplate (15), the upper housing part and the baseplate forming a body for the luminaire controller. A flexible light guide (13) is provided for transmitting light from the exterior of the luminaire head to a light sensor located within the controller (6). A lens (14) may be provided at one end of the light guide (13) at the wall of the luminaire head with the other end of the light guide being adjacent the light sensor. A terminal strip (36) and an antenna jack (37) are provided to which respective electrical connections can be made and an antenna (12) can be connected by means of an antenna cable (38).