Jim Parsons tells David Tennant why he quit The Big Bang Theory

"Our final contract was for the last two years, but no one knew when we signed it what that would mean," he said. "I kind of had a suspicion in my heart that that was going to be it for me when I did sign that contract."

He said that his feelings of wanting to leave were affirmed after the Emmy-winning actor became overwhelmed with filming the show, rehearsal for a play, appearing in an Intel commercial while his dog's health was declining. "I was exhausted. I was really upset about, more than anything, one of our dogs was getting really at the end of his life around then."

Parsons added that a few days after his dog was put down, he slipped and broke his foot whilst on stage. "It was the scariest moment for the next couple of days because I felt like I was at the edge of a cliff. I was teetering and I saw something really dark below between the death of the dog."

"The bottom line was that it was a really intense summer. The dog passing away, he was 14, and Todd and I had been together for 15 years at that point, so it just was the end of an era. I had this moment of clarity that I think you’re very fortunate to get in a lot of ways, of going 'Don’t keep speeding by'. You know? 'Use this time to take a look around.' And I did."

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He added that after realising that he would be just six years younger at the end of season 12 than his father was when he passed away aged 52, he decided to leave the show. "I think there's other things I need to try and do. I don't even know what they are, but I can tell that I need to try."

Parsons, who won four consecutive Emmy Awards for his portrayal of Sheldon Cooper in the CBS sitcom, also said that he didn't want the show to stop after he left. "I never had feelings of not wanting the show to go on without me. In fact, I kind of felt the opposite about it."

"I had a feeling of 'there's so much good going on here, so many people love it'."

The Big Bang Theory, which first aired in 2007, ended in May last year, after 12 seasons.

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