Polythene inslated cable with a pvc sheath to BS1557. So 3-cores, red, white & blue, no earth, Imperial 3/0.29 I think, 3 tinned strands per core equates to about 1.5mm2. It was like new. Found in a time warp, unfinished outbuilding of an elderly neighbour.
BS1557 was withdrawn in 1954!