Written by Matt King (Peep Show) and Steve Edge (Phoenix Nights), this warm-hearted comedy-drama follows working-class clan the Starlings, led by dad Terry (Coyle) and loving wife Jan (Lesley Sharp).
Digital Spy and a few other reporters caught up with Brendan to chat about his new role, his thoughts on British comedy and breaking away from Downton Abbey...
What appealed to you about Starlings?
"First of all, I found it very very funny. I read episodes one to three and I just felt this great warmth towards these characters. It made me laugh out loud and I just love these characters. There's no kind of tension or confrontation for a family thing and I just thought, 'This is really lovely, so I'm going to meet them for this'."
What's it like having Lesley Sharp as your wife?
"It's a dream. I always knew I'd work with Lesley - I always believed our paths would cross but I thought it would be in some Greek drama killing each other, or... some blood and guts thing! Instead it's this, and it's a dream. She's a dream to work with."
Do you see yourself as a dramatic actor or a comedic actor?
"I see myself as an actor and I don't differentiate between those two disciplines at all. I think great humour lies in playing the truth of a situation. I see myself as a performer and that applies to a Greek drama or a modern comedy."
Do you find comedy more difficult than drama?
"Yes, the timing has to come in to play and a certain rhythm. I mean, gags and humour are written in a specific way and it has to be relayed in a certain way.
"You can't be a casual observer of something humorous - you have to engage, you have to find it funny for the relationship between actor and audience to work. So I guess that's where the problem lies, but this show just works, I think."
Your character in Downton Abbey can be quite dour - was it a relief to do something lighter?
"Around about the time this came around, I was offered a couple of other moody men - you know, moody men in a cloak, moody men with a knife! So maybe something made my barometer go, 'Let's go that way - just be around funny people for a while'."
So what sort of character is Terry?
"He's big-hearted, I think he's a bit bemused - he sees the world as a gallery of characters who don't see the world as he sees it. So myself and Lesley are the heart of the Starling family, and we're both trying to throw our arms around the family and the world.
"They have one grown-up boy who won't leave home, we have Granddad - he's moved in as a result of a court order. There's one long-lost son looking for his Dad and a cousin who has just been kicked out by his girlfriend, so they inadvertently come together."
Matt King and Steve Edge wrote the show and also star - is it strange acting alongside the writers?
"I thought it would be, but it was actually great because they were there as part of the team. If anything wasn't working, they were there to tweak it. They were at the monitor the whole time, but it wasn't an oppressive thing.
"It wasn't like a gang of execs that we didn't know overseeing us. They're funny guys and nice guys to be around."
Do you think British comedy is in a healthy state at the moment?
"I think this country is really, really strong on comedy. I think with Sky and BBC Three and Channel 4, there are some great television platforms, and the stand-up movement in this country is phenomenal. It's like rock 'n' roll here.
"Britain's a funny place and there's a lot of funny people coming out of there and a lot of people are finding mediums to express themselves."
Do you think there's potential for a second series of Starlings?
"Yes, there really is. You see as the series goes on, it's so strong, so funny, so good. I think they have been commissioned to write some scripts [for series two].
"I don't know how it works for Sky, but I know the boys have been asked to write a few scripts, that's all I know. It always comes down to ratings - you always wait to see how it is received."
Starlings begins on Sunday (May 13) at 8pm on Sky1.