Line of Duty Trivia
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49 free Line of Duty trivia questions with answers — entertainment quiz, new questions added Oct 2026.
Line of Duty was turned down by BBC One as too problematic for a mainstream audience, so Jed Mercurio took his anti-corruption drama to BBC Two in 2012 and built it into the most-watched British drama since records began. The format barely changed across six series: Superintendent Ted Hastings, DS Steve Arnott and DC Kate Fleming of AC-12 investigate one guest-star copper a year while a bigger conspiracy about a senior officer known only as "H" ticks away underneath. These 49 questions cover the whole run, from Tony Gates and TO-20 to the lockbox under the workshop floor. Expect Lindsay Denton and the Caddy, Roz Huntley's hand, the £50,000 in a hotel room, Operation Pear Tree and Operation Lighthouse, the Sport Relief sketch with Lee Mack, and the Belfast buildings that stand in for police headquarters. Easy questions stick to the three leads and the guest stars; the expert tier asks about cinematographers, composers, a balaclava shortage and the actor who quit series two after two days. Every answer is cited to a page we checked, with a short explanation so you pick something up even when you miss. Mother of God, fella — no pressure.
30 of 49 questions with answers and explanations. Play the quiz
Q 01Who created and wrote every episode of Line of Duty?
Jed Mercurio
Jed Mercurio says he planned the hunt for "H" from the start, giving several characters names beginning with that letter so he could keep viewers guessing and still change his mind.
Q 02In Line of Duty, Superintendent Ted Hastings insists he is interested in one thing only: catching what?
Bent coppers
Bent coppers: the line fits a part that was first written as a jaded timeserver, until the actor's fiery audition persuaded the creator to turn him into a zealot.
Q 03On which channel did Line of Duty first air in 2012?
BBC Two
BBC Two took it after BBC One passed, fearing a drama about police corruption might be "problematic for a mainstream audience"; five years of record ratings later, the bigger channel took it back.
Q 04In Line of Duty's series 5 finale, a dying officer's twitching fingers are decoded as which kind of message?
Morse code
Morse code: he had been tapping four dots, the letter H, which AC-12 took to mean four corrupt insiders; the extra footage had been shot two years earlier and held back.
Q 05Which Scottish actor plays DS Steve Arnott in Line of Duty?
Martin Compston
Martin Compston drops his own accent to play Arnott as an Englishman; an actor who lost out to him at the auditions was cast as a fellow detective instead and stayed for three series.
Q 06Vicky McClure plays which AC-12 officer in Line of Duty?
Kate Fleming
Kate Fleming is the unit's undercover specialist: viewers first meet her as a new recruit to a suspect detective's squad, and only later learn she was spying on him for anti-corruption all along.
Q 07Who plays Superintendent Ted Hastings in Line of Duty?
Adrian Dunbar
Adrian Dunbar was only a supporting player in series 1; the reaction to his character was so strong that he was brought back and promoted to the main cast for series 2.
Q 08Which actor plays DCI Tony Gates, the detective under investigation in series 1 of Line of Duty?
Lennie James
Lennie James's Officer of the Year ends the series by stepping in front of a lorry, asking with his last words to be reported as killed in the line of duty.
Q 09Which actress plays DI Lindsay Denton, the officer under investigation in series 2 of Line of Duty?
Keeley Hawes
Keeley Hawes was meant to appear for one series only; viewers took to her tormented detective so strongly that the creator tore up his plans for series 3 to bring her back.
Q 10Which actor plays firearms officer Sergeant Danny Waldron in series 3 of Line of Duty?
Daniel Mays
Daniel Mays was billed as the new lead and shot by the end of the first episode: the plan for the series had changed, and his character made way for two returning ones.
Q 11Which actress plays DCI Roz Huntley, the detective under investigation in series 4 of Line of Duty?
Thandiwe Newton
Thandiwe Newton, a Hollywood name who wanted to work in Britain again, plays a detective who charges the wrong man and then swaps blood samples at a crime scene to cover her own tracks.
Q 12Which actor plays undercover officer John Corbett in series 5 of Line of Duty?
Stephen Graham
Stephen Graham prepared by quizzing a friend in Army intelligence who had worked undercover for real; his Corbett is in so deep that he leads the gang's armed raids himself.
Q 13Which actress plays DCI Joanne Davidson, the detective at the centre of series 6 of Line of Duty?
Kelly Macdonald
Q 21Which AC-12 officer shoots Lindsay Denton dead in series 3 of Line of Duty?
Dot Cottan
Dot Cottan offers her money for the list of abusers she has dug out of a dead man's emails; she sends it to Hastings instead, and he kills her for it.
Q 22Which senior officer accuses Ted Hastings of being "H" in series 4 of Line of Duty?
Derek Hilton
Derek Hilton plays Hastings a dying man's recorded words as proof, but it is Hilton himself who has been feeding the gang, and he is found dead before AC-12 can arrest him.
Q 23What does Roz Huntley lose to an MRSA infection in series 4 of Line of Duty?
A hand
A hand: the wound she is hiding dates from her struggle with a forensic officer, and when the bacteria in it are traced back to him the infection becomes evidence that she killed him.
Kelly Macdonald's detective leads a murder inquiry by day and takes orders over a laptop at night, in a flat the designers built as a lonely bunker.
Q 14Which misspelt word in messages to the crime gang finally exposed the Fourth Man in Line of Duty?
Definately
Definately: a junior detective trawling old case files found the same slip in one officer's handwritten notes, matching the laptop messages that had been ordering the gang's killings.
Q 15In which city was the first series of Line of Duty filmed?
Birmingham
Birmingham was meant to be the setting too, until BBC lawyers advised late on against naming a real city or a real department; the story moved to a fictional force in an unnamed Midlands city.
Q 16From series 2 onwards, in which city was Line of Duty filmed?
Belfast
Belfast plays an English Midlands city without anyone on screen saying so: a government agency's office block is AC-12's base, and the Central Library doubles as police headquarters.
Q 17Roughly how many people were watching live as Line of Duty's series 6 finale unmasked the Fourth Man?
About 13 million
About 13 million: the overnight audience peaked at 13.1 million, the biggest for a UK drama episode, soaps aside, since modern records began in 2002, though the reveal itself split viewers.
Q 18Who is finally unmasked as "the Fourth Man" in Line of Duty's series 6 finale?
Ian Buckells
Ian Buckells had looked too much of a blunderer to be the villain, which was his cover; he calmly asks for immunity and witness protection, is told he qualifies for neither, and is arrested.
Q 19In Line of Duty's early series, what codename is given to the crime gang's man inside the police?
The Caddy
The Caddy once carried golf clubs for the gang's boss; viewers knew exactly who he was from the end of series 1, so the suspense lay in whether AC-12 would ever catch him.
Q 20Which three-word text summons an armed escape during an AC-12 interview in series 3 of Line of Duty?
Urgent exit required
Urgent exit required: seconds later an armed officer bursts in to free the cornered mole, starting a shoot-out and chase that the show's makers argued over as too far-fetched.
Q 24Whom does Roz Huntley frame for the killing of Tim Ifield in series 4 of Line of Duty?
Her husband
Her husband: she lets Nick be arrested for a death she caused herself, and confesses only when evidence turns up in woodland she was seen driving to; she gets ten years.
Q 25In Line of Duty series 5, what is the codename of the undercover operation that embedded Corbett in the OCG?
Operation Pear Tree
Operation Pear Tree put an officer so deep inside the gang that he was leading its raids, and the legal adviser who helped choose him was secretly working for the gang herself.
Q 26In Line of Duty series 6, the investigation into journalist Gail Vella's murder is known as what?
Operation Lighthouse
Operation Lighthouse is led by a detective who keeps steering it off course: she overlooks that the victim was making a podcast on police corruption and that her home had been ransacked.
Q 27In Line of Duty, the murder of Gail Vella was based on the 2017 killing of which journalist?
Daphne Caruana Galizia
Daphne Caruana Galizia, Malta's best-known investigative reporter, was killed when her car was blown up after years of exposing corruption; the fictional victim borrows her maiden name, Vella.
Q 28In Line of Duty's very first scene, armed police kill an innocent man they have mistaken for what?
A suicide bomber
A suicide bomber: the raid hits the wrong flat, and Steve Arnott's refusal to help cover it up lands him in anti-corruption; the scene drew on the 2005 shooting of Jean Charles de Menezes.
Q 29What is the name of the boys' home at the centre of the abuse storyline in series 3 of Line of Duty?
Sands View
Sands View put a real scandal on screen: the storyline referred to Jimmy Savile by name, and a nervous BBC had to be talked into leaving the reference in.
Q 30In Line of Duty series 6, Davidson's murder squad is based at which police station?
Hillside Lane
Hillside Lane, the Hill to its officers, gives AC-12 an early humiliation: they storm in to seize the case files and leave with nothing, because a former colleague now on Davidson's team has tipped her off.