Yelland’s place in the story is clearest when the police discover that Simon is alive. Simon has met Honor and his son, then concealed a large amount of cash inside the Kingdom & Kingdom office. When the police find out about his return, Peter’s family problem becomes an active police matter and Simon is arrested. Yelland’s appearance belongs to that change in the episode: the practice cannot treat Simon’s presence as a private reunion once a hidden cache and a police discovery are involved. The event puts Peter between his professional duties and his feelings about his brother, while the office itself becomes part of the investigation’s immediate setting.
The same episode gives Peter a separate case involving an older man and a younger nurse. The client’s relationship has prompted concern from others, so Peter must hear the wishes of the person at the centre of the dispute while people around him form their own views. That case runs alongside the police response to Simon, but the two situations call for different kinds of judgement: Peter’s client needs advice about choice and personal relationships, while Simon’s arrest brings formal procedure into the office. Yelland’s role makes that boundary visible without taking the programme away from its focus on Peter, Lyle and the families affected by their work.
Reveal full character arc — spoilers
Across the Series
DC Yelland appears when the Kingdom family’s troubles cross into police business. His work brings formal procedure into a town where Peter is often asked to resolve disputes through conversation and legal advice.
The episodes involving Simon make that boundary especially visible: a disappearance, a return and an arrest all affect the practice and its family. Yelland’s presence gives those events a public and procedural consequence alongside their private impact.
Relationship lens
Yelland marks the boundary between Peter’s informal problem-solving and formal law enforcement, a boundary Simon’s actions repeatedly force the family to cross.