Michelle Dockery and Maggie Smith in ‘Downton Abbey: A New Era.’.Credit : Ben Blackall/Focus Features

Michelle Dockery recalls the “mixture of excitement and nerves” she felt while working with Dame Maggie Smith on the PBS drama Downton Abbey.

“I’ll never forget the first day we were filming with her, and it may have been the first ever day of the series,” Dockery, 43, says of filming a scene with Smith and on-screen sisters Laura Carmichael and Jessica Brown Findlay.

“It was a dining room scene, and she was so kind to Laura, Jessica and me. We were so young and so in awe of everyone and nervous. Maggie put us at ease. She could just crack a joke and just relax us all,” she continues in PEOPLE’s new special edition about the making of Downton Abbey: The Grand Finale.

Dockery worked with Smith on the soapy historical series, which depicted the upstairs/downstairs drama at the estate of a fictional aristocratic family, the Crawleys, and the domestic staff who serve them.

The actresses also appeared in two subsequent films, 2019’s Downton Abbey, and 2022’s Downton Abbey: A New Era, which saw the death of Smith’s character, the formidable (and quotable) Dowager Countess, grandmother of Dockery’s Lady Mary.

Smith herself died in Sept. 2024 at the age of 89.

Dockery, who reprises her role as Lady Mary in Downton Abbey: The Grand Finale, ”felt very privileged” to work alongside Smith, playing her granddaughter.

“Whenever there was a scene between Mary and the Dowager, I would read the scripts and if I saw that there was a scene between the two of us, I’d have this kind of mixture of excitement and nerves, because you really up your game,” she adds.

“Working with someone like her, you bring your A game, and those were unforgettable, those things. I remember every single one and how they felt,” says Dockery.

Dockery also says the new film “is partly a tribute to Maggie and to the dowager.”

Filming was already wrapped on the third movie by the time Smith — who opted not to reprise her role — passed away. But Elizabeth McGovern, who plays Smith’s on-screen daughter-in-law Cora Crawley, says she still loomed large: ​​“I felt her spirit was there, and we were always referencing her.”

Downton Abbey: The Grand Finale is now playing in theaters everywhere.