I was a very young controller at Eastern Radar 1966-1969. I have taken the photo attached of one of my chinagraph pencils with the serial number 48-358. On my second tour at RNAS Foulmer (Lossiemouth) the navy kindly issued me with a leather chinagraph pouch.
I suspect that more airmisses were caused by chinagraph wax obscuration than controller incompetence!!!