Director Phyllida Lloyd is to make her movie debut with a version of the hit stage musical Mamma Mia!, it was announced this week. Even with Meryl Streep already signed up, I wince to hear that another British theatre director is diversifying into film. The results often seem like the artistic equivalent of a pension investment.
Plenty of great film directors have backgrounds in theatre - Orson Welles being the most famous example - but knowing how to direct a play is no guarantee that you'll make a decent movie. The roll call of contemporary British stage directors who have been left with celluloid egg on their faces is impressive.
Odd forays into film are almost obligatory if you've ever run the National Theatre or the RSC: Trevor Nunn and Adrian Noble have both provided us with polite cinematic plods through Shakespeare. I'm a fan of Nick Hytner's theatre work, but someone should tell him to put the movie camera down and back away slowly with his hands up. The History Boys and The Madness of King George were serviceable extensions of stage plays, but still, there's no excuse for the lacklustre film of The Crucible, or the plain idiotic The Object of My Affection.
Then there's Sam Mendes, erstwhile theatrical golden boy and director of increasingly hollow films, whose reliance on sleek cinematography becomes more apparent with every picture he makes. And does anyone remember Peter Hall's Never Talk to Strangers or Matthew Warchus's Simpatico? No? Just as well, really.
There are some notable exceptions to the rule that talented British theatre directors generate cinematic dross: Stephen Daldry, for starters. It could all have gone downhill after Billy Elliot, but The Hours felt like a proper movie despite Nicole Kidman's silly plasticine nose. And while Richard Eyre was responsible for the poundingly dull Stage Beauty, advance word about his Notes on a Scandal is good.
Elsewhere, directors with a particular genius for the visual are sticking with theatre. Katie Mitchell's mesmerising production of Iphigenia at Aulis was, at times, like watching a loop of 30s or 40s newsreel. The drama swept you up, but it was the way Mitchell allowed your eyes to wander across the wide Lyttleton stage, catching minute details as well as the big picture, that made this an extraordinary study in looming terror. Mitchell might succumb to the lure of movies, but I doubt it: she doesn't need 24 frames a second to show us something new.