Complex sentence: The movie was written by Eric Ambler specifically as a comedy thriller vehicle for Margaret Lockwood in the vein of her earlier hits, "The Lady Vanishes" and "Night Train to Munich".
Split into simpler sentences: The movie was written by Eric Ambler specifically as a vehicle for Margaret Lockwood. It was a comedy thriller in the vein of her earlier hits, "The Lady Vanishes" and "Night Train to Munich".