These are from the cutting engineer (generally speaking). I remember reading about this back in the 70s, in an article about George Peckham. Here's what wikipedia has to say about him:
George "Porky" Peckham is a British record cutting engineer, widely recognised as among the most accomplished in the business. He has been responsible for producing the master discs from which countless vinyl records have been pressed over the last 40 years.
His master discs, and the records produced from them, are known as "Porky Prime Cuts" and often bear either the motto "A Porky Prime Cut" or a cryptic or humorous comment (signed "Porky"), etched into the run-out groove. Other inscriptions attributed to him include "Pecko" and "Pecko Duck"
http://en.wikipedia.org/wiki/George_Peckham
George "Porky" Peckham is a British record cutting engineer, widely recognised as among the most accomplished in the business. He has been responsible for producing the master discs from which countless vinyl records have been pressed over the last 40 years.
His master discs, and the records produced from them, are known as "Porky Prime Cuts" and often bear either the motto "A Porky Prime Cut" or a cryptic or humorous comment (signed "Porky"), etched into the run-out groove. Other inscriptions attributed to him include "Pecko" and "Pecko Duck"
http://en.wikipedia.org/wiki/George_Peckham