The Big Bang Theory could have gone on for at least “two more years”, according to one of the show’s key crew members.

The long-running sitcom came to an end last year after 12 seasons, though production designer John Shaffner has claimed that there were plans to make even more episodes until Sheldon Cooper actor Jim Parsons decided to quit.

Recalling the moment he learned the show was coming to an end during a production meeting, he told Metro: “We got up and left and they started doing the table read and somewhere during that time word had got out that it was the last year.

“The news that it was ending had been leaked because Warner Brothers had prepared a proper roll-out of explaining it to everybody, but the cast didn’t know.”

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He went on to explain: “What had occurred was Jim Parsons had been in touch with [co-creator] Chuck Lorre over the hiatus week and had said he couldn’t come back and do anymore.

“And Chuck had always said if one member of the cast left the show then the show would have to end. Warner Brothers and CBS wanted to sign for about two more years.

“I was back in the office and I found out about this and I went down to stage and I saw Johnny [Galecki] and Kaley [Cuoco] in the comic book store and they were just hugging each other and crying.

“It was very hard for a while for people to accept the decision and the crew was very disappointed because it was a good job.”

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However, Shaffner admitted that he “really respected” what Parsons did, adding: “It’s better to leave on top. I really appreciate where he was coming from in his head. I knew it was hard. He had a lot of the hardest lines to say.”