The thing about the Powell & Pressburger movies is that they were true collaborations, a rare thing in movies. Michael Powell did almost all the direction and had a hand in the writing; Emeric Pressburger did almost all the writing and had a hand in the direction, and they both functioned as producers. Kevin Macdonald's biography of his grandfather is a miracle of graceful writing, objectivity, clarity and balance, especially when you consider that grandchildren don't usually write about their own grandparents with anything like these qualities. Pressburger's strengths as a writer (and weaknesses as a director - he didn't get to direct much by himself) are clearly brought out.
Pressburger's craftsmanship, intelligence, very un-English sense of romance and his shrewd outsider's perspective English (and Scottish) life gave him an edge that many native English scriptwriters lacked, and it's surely one of the main reasons why Powell & Pressburger's films endure today while those of their contemporaries remain mostly unwatched and unloved. Powell's wizardry with the camera had much to do with it, but so did Pressburger's genius with script. It's notable that after the partnership ended, Powell made only one unequivocally brilliant film, "Peeping Tom", and it was so disturbing to its original audience that it held him back for years - and Pressburger's career more or less ground to a halt. They needed each other. Luckily for them both, there were a good few years when they each realised it, and the result is a crop of magnificent movies that will be watched as long as the medium survives.