Downton Abbey newcomer Paul Giamatti reportedly found it hard to adjust to filming on the set - instead finding it very different from the sort of productions he is used to.
The American actor, who appears in the Christmas episode as Cora's playboy brother Harold Levinson, apparently was taken aback by the calm atmosphere and amount of tea drinking on offer.
"He was like 'This is great, but is this really it?'" revealed co-star Laura Carmichael in an interview with Grazia magazine.
"I’d be like 'Yes, but there is a subtext, you know, so we’ll do our looks and our eyebrows and then the butler pours the tea …there aren’t any car chases or anything'."
She added: "He found it very bizarre and English."
Laura added that Shirley MacLaine, who also returns to the show as Martha Levinson, had now become a fully-fledged part of the Downton family.
"We were talking about Justin Timberlake one day and she said 'Justin is a sweet boy',' the actress recalled.
"Wow. Shirley MacLaine and Justin Timberlake hanging out. That's cool."
The festive episode will be aired on Christmas Day on ITV at 8.30pm.
