Robert Lines

Robert Lines, often just called Bob, was a policeman. His titles over his career included sergeant during the 1970s and inspector by 1989, a rank he still held in the 2000s.

20th century
As a sergeant in Smallmarshes, Lines informed the Third Doctor on the disappearance of Marc Marshall and the emotional state in which they found Barbara Redworth. However, he would not let the Doctor see the cottage where Redworth was found until the following morning. (PROSE: The Scales of Injustice)

Some time after Line became a Detective Inspector for the Brighton CID, he was helped by the Sixth Doctor in thwarting the Master's attempt to hack into Dow-Jones and Fort Knox. In return, he aided the Doctor's fight against SenéNet in 1989. (PROSE: Business Unusual)

In 1991, he met with Melanie Bush when she returned to Earth after her years of travel with the Doctor. He listened to her describe her experiences, then assured her that her parents missed her and would be "overjoyed" that she was home, even offering to give her a lift to Pease Pottage. (PROSE: Missing, Part One: Business as Usual)

Lines retired from the police in 1993. On his retirement day, Trey Korte came, seeking safety from the Magnate. When Trey fell into a self-induced coma, Lines contacted the Doctor. (PROSE: Instruments of Darkness)

21st century
By the 2000s, Lines was working for West Ealing Police as the Chief Inspector. (PROSE: The Lost Boy) When Mr Smith falsified the identity of Sarah Jane's adopted son Luke's identity as the son of two disguised Slitheen as part of Mr Smith's plot to destroy the Earth with the Moon, Lines conducted a missing person's report on television with Luke's supposed parents, Dax Fex Fize and Bloorm Vungah Bart Slitheen. While Sarah Jane was taken in for questioning at the police station, Luke went to live with the Slitheen, whom Lines believed were his real parents. After reading files on Sarah Jane from UNIT, Lines suspected her "powerful friends" of a cover up, but had no real evidence to hold her. (TV: The Lost Boy) Even though Lines investigated Sarah Jane Smith, and Luke's life with her, he did not think about investigating the past of the disguised Slitheen. (PROSE: The Lost Boy)

Other realities
A version of Lines, known as Praetor Linus, existed in an alternate timeline where the Roman Empire never fell. He was stationed in Sussex and knew that timeline's Sixth Doctor. (PROSE: Spiral Scratch)

Behind the scenes
Lines is not identified by name on screen in The Lost Boy. The name appears in Gary Russell's novelisation, and that work was what linked the inspector to the police officer from Russell's earlier novels in the Virgin Missing Adventures and BBC Past Doctor Adventures series.