Birkin has also worked as an actor in film and theatre. He appeared in two episodes of "": in the 1990 episode "" as René Picard, Captain Jean-Luc Picard's nephew; and the 1992 episode "", as a young Jean-Luc Picard. His film credits have included roles in "The Return of the Musketeers" (1989, as Louis XIV), "Impromptu" (1991), "Les Misérables" (1998), "All the Queen's Men" (2001), "Charlotte Gray" (2001), and "Sylvia" (2003). In 2010 he appeared in "Ourhouse" by Nathaniel Mellors.