LINE Of Duty star Martin Compston has said Sunday's episode could be the last ever - but has promised fans a "perfect ending".
The 36-year-old actor, who plays DI Steve Arnott, said the cast haven't been told the drama will return.
It came after the show's creator, Jed Mercurio, warned: "We’re in a situation where it’s not entirely clear that there will be a seventh series."
Martin told podcast : "It's different elements this year, because we have to look it in terms of, do people want us back? You don't want to overdo it.
"Ten years in you start to think of legacy, and if it goes down that well it might be the perfect ending.
"But then we might go another couple of months and... what I will say is we won't do one just for the sake of doing it.
"We don't know [if there will be another series]. That's nothing new. Jed will only do it if there's a story to be told."
He added: "Jed always takes time after a series, like a couple of months.
"There's a lot of stuff above my pay grade like analytics and audience scores. He takes the emotion out of it and looks at all that."
A trailer was revealed ahead of the big finale on Sunday suggesting plots dating back years will be tied up.
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A caption on the screen declared: "Every investigation has led to this."
There is little doubt the BBC will be desperate for the show to return for a seventh series, after ratings reached 11million on Sunday.
That made it the most-watched TV show since Doctor Who’s Christmas Day special in 2008, which was seen by 11.7million.