Smith first arrived at Sun Hill police station as a police constable (PC), having served with the Queen's Royal Fusiliers. He later left Sun Hill to take up a position in the Specialist Firearms Command (then known as SO19), but returned two years later as a sergeant. In 2009 he was promoted to inspector after Rachel Weston took up a position with Superintendent John Heaton's People Trafficking Unit.
In 2001 Smith left Sun Hill because he felt that the many new rules Superintendent Tom Chandler was introducing prevented him from enforcing the law. When Sergeant Bob Cryer, who had also served with the Fusiliers, encouraged him to pursue his ambition to become an armed police officer and gave him the highest possible grading, Smith submitted his SO19 application.
Meanwhile, Smith and PC Nick Klein were frequently called out to the home of Frank Kennedy, an elderly man whose house was continually being vandalized by youths. Kennedy accused the police of doing nothing about it and threatened to tackle the youths himself. To Nick’s surprise, Smith showed sympathy towards Kennedy, as he suspected property developers were paying youths to harass residents that were refusing to move, like Kennedy.
On one such call-out, Smith and Klein found that Kennedy had shot a young intruder dead. Klein's report to Chandler led to an allegation that Smith had encouraged Kennedy to take the law into his own hands. Believing he had lost his chance to get into SO19, Smith assaulted Nick, accusing him of being a grass and showing no loyalty. Consequently, Smith was suspended from duty.
While the Kennedy shooting was under investigation, Smith, although suspended, went under cover and, with the help of Cryer, managed to expose the conspiracy between the developers and the youths. Cryer researched Kennedy’s past and discovered that he had a criminal record for dealing in firearms. This was enough for Cryer to persuade Kennedy’s lawyer to drop the allegation against Smith. Upon Smith’s return to duty after being cleared, Chandler approved his application to join SO19.
On Smith’s first day with SO19 after completing his training, a man called Chris Finnessey, who had been refused access to his son, had taken Cryer and school teacher Rachel Bonnigton hostage and was demanding to see his son. In an attempt to avoid fatalities, Chandler handed the boy over to his father in exchange for Bonnigton. When Finnessey tried to escape in a getaway car with his son and a handcuffed Cryer, he was attacked by his enraged wife, who was trying to retrieve her son. Smith opened fire on Finnessey when he saw him trying to stab his wife, but at the same time Cryer jumped in the way, trying to separate Finnessy and his wife, and Smith's shot hit Cryer. As a result of his injury, Cryer was forced to retire on grounds of ill health. Cryer bore no malice, and he encouraged his other colleagues to take the same view. Smith's superiors agreed that Cryer's shooting was not a result of any incompetence, and Smith was allowed to continue his work with SO19.
Two years later, in 2003, Smithy returned to Sun Hill as the new sergeant, after the death of Sergeant Matthew Boyden, who served at the station from 1991-2003. He formed a very close friendship and working relationship with Inspector Gina Gold, but he was accused of homophobia and racism, and he joined PC Gabriel Kent's 'SWAMP' (Straight White Male Police Association). However, he then showed a more sensitive side when he was the one to find DC Mickey Webb after he had been raped.
On Smith's first day as sergeant, he kissed PC Kerry Young. They agreed to go out for a drink, but then he backed out, saying that a romantic relationship between a Sergeant and a PC would not work. While observing on a gang of teenage joyriders, Young seduced Smith in the car, but they were caught half naked on the back seat. Thereafter Smith stated that their relationship should remain strictly professional.
Young began a relationship with PC Cameron Tait, of which Smith grew increasingly jealous. After an argument during a drinking session, Young and Smith had a one-night stand. Seizing the opportunity to make trouble, Gabriel Kent manipulated Young into thinking that Smith had raped her, and pressed her to make an official allegation. She decided against it, but Kent spread word around the station. Andrea Dunbar leaked the rumour to the press, and the station was divided. Even when Young realized that Smith was incapable of rape and dropped the allegation, his reputation was severely tainted.
Young discovered that Kent was working in the police under a false identity and that Dunbar was an undercover journalist. Planning to reveal all she knew before resigning from the Police Force, Young declared her love for Smith. Moments later, however, determined to stop Young from exposing him, Kent shot her from the rooftop with a sniper rifle. She died with Smith at her side shortly after arriving at the hospital.
While investigating a car theft, Smith met Louise Larson, wife of gangster Pete Larson. He was frustrated by her unhelpfulness, but also attracted to her, and they embarked on an affair. When Pete Larson found out, Smith was abducted at gunpoint, beaten up, bound, gagged and driven in the boot of a car to an empty warehouse. Larson attempted to shoot him there, but the Specialist Firearms Command arrived in time to rescue him. Louise refused to testify against her husband and broke off her relationship with Smith. She changed her mind about testifying several months later, but this meant she would have to go into witness protection, and she asked Smith to move to Australia with her. However, she was killed in a hit and run incident, for which Larson tried to frame Smith. Smith was suspended from duty and charged with Louise's murder after being identified as the driver of the vehicle by a witness named Caplin.
Smith was remanded in custody but, even there, he could not stop policing, and tried to help his cellmate who was wrongly accused of drug dealing inside the prison. Meanwhile, Smith's colleagues at Sun Hill tried to prove his innocence. As a result of their work, Caplin finally admitted to lying in an attempt to solve his debt problems – Larson had given him a loan in exchange for accusing Smith. Larson was arrested at Louise's funeral and Smith later returned to his job at Sun Hill.
Smith had a brief affair with DC Kezia Walker – an open relationship without ties. When Kezia's lease expired and she was about to be made homeless, Smith offered her a room to rent. However, they soon drifted apart, and eventually split up amicably.
Smith was temporarily promoted to acting inspector when Inspector Gold took a few weeks' leave. On his first day in the job, there was an armed robbery, an escaped convict on the loose and the funeral of a supermodel, which required high-visibility police presence. In addition, PC Beth Green was taken hostage and had a complaint made against her.
When Callum Stone arrived for his first day as sergeant, a criminal fended off the officers holding him for processing and tried to escape. Stone arrived at the right moment and fought the criminal to the ground. When Smith emerged from his office, all he saw was two men fighting. He restrained Stone with a headlock, only realising that Stone was a police officer when he displayed his warrant card to Smith.
When Gold returned, Smith was relieved of his additional duties and returned to the rank of sergeant.
Smith had known sixteen-year-old Carly Samuels since she witnessed a crime on the Jasmine Allen Estate. At a party that became rowdy, Smith recognised her as she was leaving, and stopped her for more information. He was horrified when she was murdered in a drive-by shooting.
The police recovered the car used in the murder and found bullet casings that did not match up with the bullet that killed her, meaning that at least two guns must have been used. Detective Inspector Neil Manson suspected that Samuels had just got in the way of a revenge attack on her boyfriend Marlon Reed, by a man he attacked, Tito Morientes. Manson had the local canal searched, and a 9mm automatic pistol was recovered.
On the way to the murder trial, Smith's car was deliberately run off the road, causing it to flip over. When he eventually reached the trial, it was put to him that his relationship with the Samuels family was unprofessional. One of the accused, Carly's ex Dwayne Fox, changed his plea to guilty midway through the trial, with the other suspect, Tito, calling him a grass.
Smith once again came across Carly's mother Leanne, a year later during the investigation to an assault.
Smith went under cover as a gun runner called Lawrence Smith in order to expose a gun smuggling operation. DC Stevie Moss also went under cover, posing as Lawrence's girlfriend and providing information to DS Max Carter. The operation ended when Smith shot Kieran Wallace, a dangerous criminal who became a major risk to the public when Smith was exposed as an undercover police officer.
While investigating an arson attack on a school, Smith and PC Nate Roberts rescued a girl who was being beaten up by two boys in the local park. When the thugs ran off in different directions, the officers split up and chased after them. Smith was stabbed and sustained serious injuries: a lung was punctured and collapsed, and he lost four pints of blood. Smith positively identified his attacker. It turned out that the fight in the park was over nothing more than a stolen iPhone. Smith recovered from his injuries and, after a short break, returned to work. The two men were later arrested.
While Smith and Callum Stone were investigating a series of crimes in the Sun Hill area, Jason Devlin and his father Matthew came to their attention. They suspected the Devlins of an assault, but could not gather sufficient evidence to arrest them. Then, when the CID investigated an illegal immigrant trafficking scheme which had resulted in death, DCI Jack Meadows and DI Neil Manson suspected the Devlins were controlling it. When Jason Devlin "discovered" these illegal immigrants in his flats, he kicked them out, causing a riot. During this riot, DC Stevie Moss escorted Jason back to his car, and when she tried to examine a bag in the boot, he beat her up. Witnessing this, Smith became enraged, and he in turn beat up Devlin. Stone arrived moments later to find Moss and Devlin unconscious and Smith staring at Devlin in despair. Stone persuaded him to keep quiet about the incident, on the grounds that Devlin deserved what he got and Smith was too good a policeman to lose, but Devlin made a complaint of assault against Smith, and a witness was found to corroborate it. However, Smith's colleagues found enough evidence to arrest Matthew Devlin for kidnapping a little girl in order to intimidate another witness against Jason, who faced other charges. When Jason's barrister expressed disbelief at Smith's account of events, he simply replied that that was why he was a police officer and she (the barrister) was not. After the key witness for Sun Hill arrived at court to give evidence, even after intimidation by the Devlins, Jason changed his plea to guilty.
During the Devlin investigation, Superintendent John Heaton announced that he was leaving Sun Hill and asked Rachel Weston, DS Stuart Turner and Kezia Walker to join him. Jack Meadows, the newly appointed Superintendent, asked Smith to be the new Inspector.
The first major incident Smith had to deal with after his promotion was a brawl outside a nightclub. An allegation of assault during this brawl caused Callum Stone to be suspended. Smith's fellow officers felt that he and Sergeant Jo Masters were failing to support Stone, and both started to lose the respect of their teams. Ricky Hollands was the one and only guy who could clear stone , Respect was regained when Nate Roberts overheard Masters defending the team during an argument with Max Carter. Later, when PC Mel Ryder rescued a young boy from drowning in a flooded drain, she herself then became trapped, putting her life in jeopardy. Smith, however, entered the drain and rescued the young PC, to a hero's applause.