There's a role on Peaky Blinders if Line of Duty star Stephen Graham wants it - but it won't be Al Capone.

When the legendary Chicago gangster was name-checked at the end of the Cillian Murphy-starring BBC gangster drama's fourth season, fans went into overdrive, assuming Graham would get the role he played a few years ago on Boardwalk Empire.

Peaky Blinders creator Steven Knight said that Graham is the person he most wants to make a guest appearance but denied he would play Capone - and added that he has already devised a role in the show for him.

He told the BBC's Obsessed with . . . Peaky Blinders podcast: "We're proceeding with that, but not this series. Not Al Capone, I didn't want to go west. Once you go into Chicago gangster . . .

"I referred to him last series, but I didn't want to go into that."

But he was willing to discuss some of the rumours surrounding potential Peaky Blinders guest stars, and why he'd approach the idea with a certain trepidation.

Cillian Murphy in Peaky Blinders

"The amount of people who have come to us wanting to be in it is quite astonishing - and really good people. What I've tried to avoid before is turning it into a 'spot the celebrity', you know, because I think it's quite distracting sometimes.

"But someone like Adrien Brody is a great actor, obviously you want to put them in it, but I think now we're coming to the final two series, I'm going to relax and open the gates a bit because there's some amazing people who want to be in it, and I think 'Why not?'"

Asked what kind of role he does envisage for Graham, he replied: "I've already got it and I'm not going to tell you."

Knight also addressed rumours that Julia Roberts was interested in a part in the show, saying: "I don't know where that got out, but, yeah, fingers crossed on that."

Julia Roberts

Previewing the forthcoming fifth season of the show, he said: "There is a thread and a strand to it which is incredibly topical.

"Not thanks to me, but thanks to what was happening at that time. There are so many parallels.

"It's the early '30s and it's the first stirrings of fascism and nationalism and populism, and there are particular politicians that were happy to stir that up and make use of it and get votes from it.

"And Tommy has to face that and it's part of what I feel will, hopefully, eventually be a rehabilitation of him, because when he comes across that, how's he going to react? Is he going to go with it? Is he going to oppose it?"