How many movies have Helen Steinway Bailey and Nina Armstrong collaborated on?

They have worked on 5 movies together! Their first movie together was Harry Potter and the Half-Blood Prince (2009) while their highest rated movie together was Harry Potter and the Deathly Hallows: Part 2 (2011). They have not worked together since Sherlock Holmes: A Game of Shadows (2011). They are most known for their adventure films together.