That looks like one of those old T&E glands, ...do they still make them things??
Dave, i think what you are talking about, was a spiral armoured cable that was once quite popular (maybe still is) on factory machines and machine tools that used a very similar type gland to that shown...
Both of these glands may have changed due to IP requirements that are now required...
I always knew them as Henley glands and the cable as metaflex, usually 3 core with rubber sheath then spiral wrapped with steel.