In the novel Sparkling Cyanide, Sergeant Pollock is a police sergeant working with Chief Inspector Kemp.
When Chloe West asks to speak to the officer in charge if the Luxembourg case, Sergeant Pollock receives a telephone call informing him of this. He tells Chief Inspector Kemp, who tells him to bring Chloe in.
After interviewing Chloe, Chief Inspector Kemp discusses what she had said with Sergeant Pollock, and then tells him to send Stephen Farraday in.