Gary Oldman has said he was not trying to be “rude” to Harry Potter fans after he criticised his own acting as Sirius Black in the fantasy franchise.

The Oscar-winning actor, 66, played Harry’s godfather and escaped convict Black from the third movie, Harry Potter And The Prisoner of Azkaban, including Goblet Of Fire and Order Of The Phoenix, and made a brief appearance in Deathly Hallows: Part 2.

He was asked at the Cannes Film Festival about saying his work was “mediocre” in the films and that he would have portrayed Black differently if he had read the books by JK Rowling, in comments made on the Happy, Sad, Confused podcast.

Oldman told the press conference for Naples-set Parthenope: “(It’s) not to disparage anyone out there who are fans of the Harry Potter films and the character who I think is much beloved.

“What I meant by that is, as any artist or any actor or painter, you are always hypercritical of your own work.

“If you’re not, and you’re satisfied with what you’re doing… then that would be death to me.

“If I watched a performance of myself and thought, ‘My God, I’m fantastic in this’, that would be a sad day.

“What I meant by the Harry Potter remark was there was such secrecy that was shrouded around the novels, they were under lock and key.

“And had I known from the very beginning, if I had read the five books and I had seen the arc of the character, I might have approached it differently.

UK premiere of Harry Potter
(From left to right) Sir Michael Gambon, Rupert Grint, Emma Watson, Daniel Radcliffe, author JK Rowling, director Alfonso Cuaron, Gary Oldman and David Thewlis at the UK premiere of Harry Potter And The Prisoner Of Azkaban (Ian West/PA)

“I may have looked at it differently and may have painted it in a different colour.

“So when I started Harry Potter all I had was the book The Prisoner Of Azkaban and that one representation of that man.

“One book in the library of Sirius Black and that’s kind of what I meant by it.

“It’s not me looking at the movie and saying ‘it’s a terrible film or I’m terrible’… I just wish it had been under different circumstances.

“That’s what I meant, (I was) not (trying) to be rude to any of the people out there who likes that film.”

Oldman was also asked about the similarities between him and US writer John Cheever, who he portrays in Parthenope, directed by The Great Beauty filmmaker Paolo Sorrentino.

77th Cannes Film Festival
Paolo Sorrentino and Gary Oldman (Doug Peters/PA)

He said there “are a few” resemblances before speaking about ageing.

Oldman said: “Age, well there’s nothing we can do about it, is there? That’s for sure but I’m the happiest I’ve been. I think I’m more comfortable now in my own skin than I was when I was younger.

“I have a terrific family… who are supportive and creative. There was chaos and drama and a lot of pain in my life when I was younger. I’ve made it no secret that I used to drink, and I’ve just celebrated 27 years of sobriety.

“Cheever, my wife (Gisele Schmidt) actually found a quote where he says, ‘My shaking hand reaches for the phone to ring Alcoholics Anonymous, and instead it reaches… for the whiskey, the gin, the vermouth’. And I’ve been there. I know what that means.

“So coming to this role, there were things that I instinctively understood.”