Adrian Dunbar has revealed that the Line of Duty cast don't always know how a series will end until the last minute.

Appearing on Good Morning Britain on Monday, the Northern Irish actor spoke to Susanna Reid and Adil Ray about season six and the most recent episode.

Commenting on the fact that viewers have to wait an entire week to see the next episodes, Adrian said: "It's great. Line of Duty does seem to be a bit old school as in people are happy to watch it, talk about it, wait for the next episode, and get back on it.

"It is that kind of show and Jed structures it so it is like that, so we have the cliffhangers. And because of the cliffhangers and the twists and turns, you can’t really leave it."

Line of Duty star Adrian Dunbar appeared on Good Morning Britain on Monday
Line of Duty star Adrian Dunbar appeared on Good Morning Britain on Monday

Discussing the ending of each series, Adrian continued: "Regarding the ending, I think Jed [Mercurio] always gives himself a bit of leeway where the ending is never set in stone and we never get that last episode until very late in the day.

"So therefore, we really don't know for the first three eps. Sometimes he doesn't know and then right at the very end he may turn round and decide to just say to one of us, 'can you just look over there and a look over here'.

Adrian plays the role of Supt. Ted Hastings in the hit BBC crime drama
Adrian plays the role of Supt. Ted Hastings in the hit BBC crime drama

"And suddenly the audience go, 'oh right, so there's a cliffhanger at the end of the series'."

Susanna and Adil were keen to ask Adrian if there will be another series of Line of Duty, but he was very cagey about it.

"I think if the numbers are good and the BBC are happy, I’m sure they’ll want to do another series," Adrian teased.

When probed if he would appear in another series though, Adrian simply replied: "I don't know."

Adrian teased that the endings of Line of Duty are 'never set in stone'
Adrian teased that the endings of Line of Duty are 'never set in stone'

And it's no surprise that he's not keen to spill the beans as he also admitted that BBC bosses give him notes about what he can and cannot say during interviews.

"The BBC’s people send me notes and say, 'you can’t talk about this, this and this'," Adrian revealed.

"Now and again, leaks do happen, and it’s a show that depends on collusion of the public."

Line of Duty continues Sunday at 9pm on BBC One.