Actor Josh O'Connor and creator Peter Morgan have heaped praise on Emma Corrin, the young actress picked to play Princess Diana in the new season of The Crown, insisting she is stunning as the late royal.

Corrin was picked because she resembled Diana, but Morgan claimed he could not have selected a better actress to get under the princess' skin.

"We spent our whole time just staring at this woman reading the lines going, 'Wow, she’s kind of perfect'," the writer explained to Town & Country.

O'Connor, who portrays Diana's husband Prince Charles in The Crown admitted he was astonished by the unknown star's talents.

"I was in awe of her," he recalled.

"This young actress who hadn’t done an awful lot, and here she was inhabiting Diana, seemingly quite easily."

Meanwhile, Corrin herself was most impressed with co-star Olivia Colman, who made her feel tense during scenes between Diana and Queen Elizabeth.

"Obviously, Olivia is the biggest ray of sunshine ever," gushed Corrin. However, when Colman stepped into character as the Queen, it was a different story, she shared.

“She just went stone cold horrible,” Corrin recalled.

“It was so hard to not take it personally.”