6mm flat twin NO earth?

It is not likely to be exactly 6mm2 either - but there certainly was 2 core cooker cable, I took some out at my parents. The earth ran as 7 strands of  bare copper nailed to the joists back to the under stairs cupboard where the consumer unit was.

The problem of the separate earth in thin strands like that is that sometimes it gets broken or disconnected by accident, so modern practice for lone earth wires requires mechanical protection or something quite chunky.

You do not say if this old cable is rubber or PVC - the conductor sizes metricated and then changed a bit (~ 1970) not long after PVC became dominant over rubber (mid 1960s). The temperature to which you can safely flash rubber for a short period while blowing a fuse is quite a bit higher, so the copper core sizes needed to meet what we now call the adiabatic requirement were not really at the forefront of thinking in the way they are today.

If it is a plastic cable it will be a very early one.

Mike

I don't really have any experience of rubber cables, i assume they are obviously rubber ie very bendy?

The cable feels farely stiff and is branded Ashathene, it is 7 strand tinned L+N.

IIRC that cable had rubber insulated cores and a plastic outer sheath.

The rubber insulation tends to deteriorate where exposed at the ends. 

Ashathene was used almost exclucivly  by electricity boards and 6mm =7/044

Ashathene was used almost exclucivly  by electricity boards and 6mm =7/044