Elizabeth McGovern (left) and Shirley MacLaine
Frederick M. Brown/Getty
07/24/2012 at 04:30 PM EDT
British TV import Downton Abbey
has found many fans in the States, but until recently Shirley MacLaine was not one of them.
"I walked in to my hairdresser lady's place in Malibu and they were talking about [the show]," MacLaine told reporters Saturday at the TCAs in Los Angeles. "I said, 'What do they mean?' Then I saw [the show], and I had three months of [filming] it."
The screen legend, 78, is joining the hit PBS series
for its third season – playing Martha Levinson, the American mother of Elizabeth McGovern
's character, Lady Grantham. The third season kicks off on PBS January 2013.
"I didn't know anything about Martha Levinson, but my hairdresser did," MacLaine said about her character, who was referenced to but never seen in the first two seasons. "Along with the great acting and writing that is why I [took the part] – to see if my hairdresser was right!"
Of her time filming in England
, the Terms of Endearment
Best Actress Oscar winner said, "I had a fabulous time." And her new costars were equally pleased to have her.
"We really miss her," said Emmy nominee
Michelle Dockery, who plays Levinson's granddaughter, Lady Mary Crawley. "She really kicked off the first two weeks of filming the third [season], and we loved working with her. Her presence was so amazing on set."
Although MacLaine is portraying an American surrounded by the British class system, it was not hard for her to imagine a life with butlers and dressers.
"The first day on set they put my costume on me," MacLaine recalled. "The buttons were so small and the zippers so [difficult] that I thought, 'Of course a class system existed. It was a necessity to get dressed!' "