Abstract: A lighting device is disclosed that comprises a glass tube (10); a solid state lighting assembly in said glass tube, said assembly comprising an electrically insulating optical film (20) comprising at least one arcuate portion lining a part (12) of the inner surface of the glass tube, wherein the glass tube further comprises a further part (14) defining a light exit portion; and a plurality of solid state lighting elements (32) on a carrier (30), said carrier contacting said optical film; a thermally conductive member (40, 42) in between at least a part of the solid state lighting assembly and the glass tube for thermally coupling the solid state lighting elements to the glass tube; and a transparent or translucent electrically insulating cover (50, 60) contacting the electrically insulating optical film and covering the solid state lighting elements. A luminaire including such a lighting device and a lighting device assembly method are also disclosed.