Sitting in the back of a cab with Sienna Miller is perhaps not the most ideal place for a married man to be spotted.

Happy happy shake: a grinning Sienna is led from The Groucho Club to nearby Jerry's Club

But that's where actor Cillian Murphy found himself last night after a drinking session with the 27-year-old actress.

The pair began their night at The Groucho Club in Soho, before leaving at 2am to head to the nearby Jerry's Club.

Refreshed: Cillian Murphy and Sienna Miller share a cab last night

They tried the old trick of walking several metres apart to avoid being snapped together, with Sienna being escorted by a bespectacled flunky.

But all that hard work went out the window when they got into a cab together at 3am to head home.

The pair met on the set of their new movie Hippie Hippie Shake, which is yet to receive a release date but is expected to appear in cinemas this year.

Notably absent was Sienna's on/off boyfriend Balthazar Getty, who reunited with the actress in November after a brief split.

The father-of-four is currently in his native America working on his TV show Brothers And Sisters. Irish actor Cillian, 32, lives in the capital with his wife Yvonne and their two children Malachy, three, and Carrick, 18 months.