Dunbar, known for his role as Superintendent Ted Hastings in the hugely popular BBC police procedural, has now landed the lead role in ITV's Ridley where he plays DI Alex Ridley.
But asked whether he was reluctant to play another cop, he told Yahoo and other media that it was what he had to do and joked about continuing Hastings' storyline.
He said: "Of, course, there would be a kind of (reticence). I think if it was a series of books, it would be called What Ted Hastings Did Next.
"However, I find, for me, once I see me as a character outside of uniform, it's a completely different character. And Ted's office-bound, uniform-bound, very tight chap, a kind of interesting, dignified and very formal character.
"Whereas this guy, he's a bit gruff, you don't feel the warmth of him at the start because of what's happened to him."
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Dunbar, who recently played a doctor in Channel 5 series Blood, added: "It wasn't a problem to do another cop. I mean, you have to be a cop or a doctor or a vet, you have to have some profession that has returning storylines."
Ridley sees Dunbar's character, a retired detective, returning to the force as a consultant after a troubled past and still struggling with personal grief.
He stars alongside Bronagh Waugh in the drama that is due to air on ITV on Sunday nights this autumn.
Meanwhile, Line Of Duty fans are hopeful that a seventh series could be on the way as star Martin Compston has said he and the other cast have met with show creator Jed Mercurio.
He told The Sun: “We sat down with Jed recently. We’ve always taken a year or two between series. This is no different.
“We won’t do it for the sake of it. We’ll do it if there’s something to tell.”
Watch: Adrian Dunbar says Line Of Duty could return as a movie