O’Connor played the royal in seasons three and four of the series, which aired in 2019 and 2020, with Dominic West since taking over the role.
In a recent interview with GQ, the actor, who won an Emmy for his performance, said he didn’t enjoy the exposure the show gave him.
“It was a f***ed-up time. I found it so impactful, people stopping me,” he told the publication. “You want to be in stuff that’s successful and seen, but I think sometimes we underestimate how powerful even a slight loss of anonymity can be.”
He added that he has found himself feeling nostalgic for the time when he was working on smaller film and TV projects, such as the 2017 indie film God’s Own Country, saying: “What I was doing in my career before The Crown – I just wanted to carry on doing that.”
Later this year, The Crown will enter its sixth and final season, and will cover the 1997 death of Diana, Princess of Wales.
Speaking as part of a panel at the Edinburgh TV Festival in August, producer Suzanne Mackie said it was important for the team behind the hit series to be “sensitive”.
She said: “The show might be big and noisy, but we’re not. We’re thoughtful people and we’re sensitive people.
“And so there was a very, very careful, long, long, long conversation about how we do it – and I hope, you know, the audience will judge it in the end, but I think it’s been delicately, thoughtfully recreated.
Diana will be portrayed by Elizabeth Debicki, known for her work in The Great Gatsby and Guardians of the Galaxy Vol 3.
Though a premiere date has not yet been confirmed, the final season is likely to follow the pattern of previous runs and launch in November.
Imelda Staunton will reprise her role as Queen Elizabeth II and Jonathan Pryce will continue to play Prince Philip.