Corrin’s performance in Netflix’s royal hit, which arrived on the platform this morning (15 November), is one of the most highly anticipated in the new episodes, which will cover Princess Diana and Prince Charles’s wedding day in 1981.
It was after filming a pool scene in Spain, however, that Corrin was hospitalised with low oxygen levels.
“I'm asthmatic and had been ill for a while with a cough," Emma told Glamour magazine.
“I had to film a scene in a freezing-cold swimming pool. It was the hardest scene to film because I was genuinely keeping myself alive treading water. We were meant to be flying back that night to the UK and went past a hospital to get antibiotics.”
She continued: “The doctors gave me an oxygen test and test and said, ‘We can't let you go because your oxygen levels are so low,’ so I was hospitalised.”
Corrin recalls the nurses asking if she would like them to “put a cardboard box” over head so nobody would recognise her.
The 24-year-old has only had a handful of on-screen parts before The Crown. She appeared in one episode of the ITV drama Grantchester, had a recurring role in the DC Comics series Pennyworth as an aspiring actor, and starred alongside Keira Knightley in the Miss World comedy Misbehaviour.
Corrin will be replaced by Elizabeth Debicki as Princess Diana in season five of The Crown, which will likely depict her death in 1997.
Watch: Is The Crown a true story?