A-lister Keira opted for a crinkled black dress with an embroidered neckline and long train, which she teamed with tousled hair and stilettos.
Elisabeth, meanwhile, worked a vivid scarlet frock, with a halterneck and a ruched waist, which she paired with nude heels and minimal makeup.
Both ladies are starring in new West End show, The Children's Hour, which sees them starring as school mistresses at an all-girls boarding school in the 30s, who are wrongly accused of having a lesbian affair.
The after-party was held at The Penthouse club in Leicester Square - and we think both ladies looked fab.
Whose dress do you prefer? Let us know below.