"A PORKY PRIME CUT" is the signature of British record cutting engineer George "Porky" Peckham.
Originally a guitarist & singer with 1960s group The Fourmost, and managed by Brian Epstein, he left & joined Apple in 1968. Peckham's signature appeared on Beatles records from that point. (Link?)
Peckham worked for Chas Chandler (ex Animals bass player & Jimi Hendrix manager) at IBC Studios in Portland Place through the 1970s cutting a lot of the punk records of the time, this is the period when the second batch of C.I.D. was pressed.
His signature also appears on Stranglehold, Tomorrows Girls & Another Kind of Blues after which Gem switched to TAPE 1 for future pressings, although Porky makes a come back in 1986 with Dojo's Subs Standards and with LINK Records 1990 re-press of Endangered Species.