As far as I know rexine was used post war….a type of faux leather.
Prior to doing my ‘53 Light 15 the original rexine was glued directly onto the wheel arches with a hessian material giving some padding. The squab and seat back rest was all leather and the seat backs(rear) were rexine.
My prewar 12 was all leather.
Alistair
Alistair