It appears to be TRS - Tough Rubber Sheathed - which is likely to be over 60 years old. The question as above is whether that point is actually in circuit, or just abandoned during a rewire. If the latter, then obviously no use re the original question of fitting a point there. If it is still in use, don't panic, the visible parts of the insulation do not look as perished as they often are, but nonetheless it should not be expected to last much longer and might be in worse condition elsewhere. That point, which by its three cables suggests a ring point with a spur, should not have been left unconvered anyway.
Have you had an EICR (Electrical Installation Condition Report) done at any time or was one done when you got the house? That would identify whether any old cable was found elsewhere. Or do you know of a date when it was definitely rewired?