A quickie on this. Based on the true-life memoir of Colin Clark (bon viveur brother of political diarist Alan Clark), it recalls the privileged Clark's entry into the UK movie industry in the 1950s under the wing of family acquaintance Sir Laurence Olivier. Assigned as third AD to a corny Olivier vehicle (The Prince and the Showgirl) starring the original manic pixie dream-girl Marilyn Monroe, Clark finds himself unofficially drafted as Marilyn's companion, initially to keep an eye on her but ultimately succumbing to her charms, becoming besotted with the troubled star.
Most notable for a solid impersonation of Marilyn by Michelle Williams, it actually offers little beyond verisimilitude. The other performances tend toward the unremarkable (excepting Zoe Wanamaker's humorous turn as Paula Strasberg, and Philip Jackson as Marilyn's hangdog bodyguard). Eddie Redmayne, the lead, is believably callow but he cannot carry the film, nor can any amount of scenery chomping from Ken Branagh as Sir Larry.
The main problem, however, is the slightness of the story. Never in itself quite enough to sustain a whole movie, it bobs along fairly pleasantly to begin with but by the half-way point it's really starting to drag. As a species of romance, it is half-baked; the jeopardy seems false and the character payoffs are unearned. As a character study, it never knows quite what to do with Ms Monroe, lapsing into some eye-rollingly horrific nudge-winking dialogue to get suggest her troubled childhood and damaged personality.