Line of Duty begins on BBC One from season one and it's a hit with viewers all over again

A rerun or not, fans were thrilled to have it back on screen. One viewer owned the entire five seasons on DVD, but that didn't stop him watching one more time.

For some viewers, it was their first viewing of Line of Duty season one and they were struck by how the cast, including Martin Compston as DS Arnott and Vicky McClure as DC Kate Fleming, looked so young.

The quality of the writing from showrunner Mercurio earned many compliments, with killer lines like "Superintendent Hastings – like the battle!" praised by many.

At the heart of the drama is DCI Gates, played memorably by Lennie James, a morally conflicted copper if ever there was one. As well as being accused of "laddering" (building up his case rate by pinning crimes on the wrong criminals), he was busy hiding a drink-driving hit-and-run fatality caused by his lover Jackie Laverty.

Gates had a dark warning for Arnott, who was suspicious of the detective from early on. "You take a shot at the King, make sure you kill him..."

The episode finished with Gates deleting photographic evidence of the hit-and-run victim, a move that had "boomerang" written all over it.

Some viewers felt Gates was actually at heart a decent man, a brilliant anti-hero because "he's basically a good guy making increasingly bad decisions".

Many Line of Duty viewers remarked on the fact the first episode laid so many of the foundations for future storylines over all five seasons.

Line of Duty season one continues on BBC One on Tuesday night and all five full series can be watched on iPlayer.

If you're looking for more to watch, check out our TV guide.