George Clooney left the 'Downton Abbey' cast starstruck when he appeared to film secret scenes.
The Hollywood actor is set to appear in the period drama's Christmas special in December, and his arrival on the set left the show's stars "falling about themselves with excitement".
An insider told The Sun newspaper: "The cast were falling about themselves with excitement and lining up to have their photos taken with George.
"The girls were mad keen to speak to him. He was full of jokes and had them all in stitches.
"'Downton' is now a global phenomenon and they are used to red carpet events with Hollywood A-listers. But this was George acting alongside them."
Laura Carmichael - who plays Lady Edith Crawley on the hugely popular ITV show - admitted George's appearance on the show was such a secret that the cast "didn't know if it would actually happen" until he arrived on set.
She said: "It was amazing. We didn't know if it would actually happen until he turned up.
"We were filming and then heard, 'He's here! He's here! He's arrived!' "
Meanwhile, it was recently revealed reality TV star Kim Kardashian West is also keen on a role.
She admitted: "I'm a big fan. I'd love to be on it if they asked. I love things like that."