Before the invention of the plastic zip tie, there were cable ties made of steel, aluminum and brass.
I suppose you would use these in places where a P-clip would not work if the screw was visible, like on a fender.
My Mark V had two of these brass cable ties holding the fog light cables to the head light cables. One was broken.
They don’t seem to be listed in the Mark V SPC under Cable Clips on page 91A.
Just yesterday I discovered that the MGTC used these same brass ties.
The TC people seem to be even more obsessive about originality than we are, so Moss Motors carries them, part number 161-800 at $5 each. I’ll post a picture when it comes.