Shirley MacLaine is playing Lady Cora's mother Martha Levinson.
Eragon star Ed Speleers will play a new footman named Jimmy.
Matt Milne ("War Horse") is a new footman named Alfred.
In addition to the new footmen, Cara Theobald will play a new kitchen maid named Ivy and Lucille Sharp will play the maid for Lady Cora's mother Martha (Shirley MacLaine) named Miss Reid.
|Lucille Sharp Cara Theobald|
In this picture from the set, we have two of the new cast members, Cara Theobald and Matt Milne:
Here we see Lucille Sharp in the front seat & Shirley MacLaine in the back:
I haven't seen anything with Ed Speleers on set yet so lets keep our eyes out Downtonians!