LONDON — Maggie Smith, who plays the sharp-tongued Dowager Countess of Grantham in “Downton Abbey,” has said that the next season of the British period drama will be her last.

The season five finale just aired in the U.S., and there has been speculation that the series will stop after the sixth season, but whatever the show’s fate, Smith told the Sunday Times her part is coming to an end.

“They say this is the last one, and I can’t see how it could go on,” she said. “I mean, I certainly can’t keep going. To my knowledge, I must be 110 by now. We’re into the late 1920s.”

But Smith, who is 80, will not be quitting acting, and will continue to work as long as she is able to.

“When you’re not working it’s scary, and when you are working it’s scary, because you don’t know if you’ve got the energy to get through the day,” she said. “But the bleakness of not doing it, and missing out on the friendships that you make, is too much to bear.”

Smith is keeping busy. She presently appears in the movie “The Second Best Exotic Marigold Hotel,” alongside Judi Dench and Richard Gere, and has just finished shooting “The Lady in the Van,” in which she plays a homeless woman.