Shirley MacLaine. (Evan Agostini)

How do I know this? The good people at Vulture have pointed out that MacLaine has been tweeting from the set.

Okay, fine, you got me: They’re not the most interesting tweets ever tweeted.

“Everything is going well. We shot outside in wind and rain. Love the cast and crew,” reported MacLaine, who will play Lady Grantham’s mother Martha Levinson, Wednesday.

And from Thursday: “Amazing day on Downton Abbey set. I love the British humor and temperament and functionality. Maggie is so subtle and so much fun!”

(Are you as jealous as I am about that Dame Maggie Smith name drop? Can you even imagine all the fantastic Levinson-Dowager Countess interactions that are being filmed?)

Sure, this isn’t much to go on. But considering season three doesn’t premiere in the U.K. until September and in the United States until early 2013, “Downton” fans should take what they can get.

In related news, the ratings for the “Downton” finale were pretty stellar: 5.4 million viewers tuned in to PBS. This is the TV network’s highest rating since Ken Burns’ “The National Parks” documentary premiered in 2009.