When DS Jones was promoted, he was replaced by DS Charlie Nelson. Nelson is the first Sergeant to not serve alongside Tom Barnaby. He is a lodger at Kate's house until her exit at the beginning of season 18. He then stays at a bed and breakfast.
Nelson is the second sidekick to work alongside DCI John Barnaby, and makes his first appearance in the Christmas special, The Christmas Haunting. Nelson is more decisive that many of his predecessors. He takes initiative and often has things done before being asked by DCI Barnaby. Nelson leaves at the beginning of season 19 to take an undercover course.
Dr. Kate Wilding
Nelson and Kate become close when he is her tenant. They have a joking relationship that resembles siblings. He often makes fun of her for her lack of housekeeping skills, and she often picks on him for being so serious.