This film is the very best thing I’ve seen Deborah Kerr do. And she’s just gorgeous too.

This is one of the joys of Powell and Pressburger - they’re usually the very best thing anyone ever does. (On a Kerr/P&P note - if you haven’t already - you should watch Black Narcissus because it is just the most brilliant thing. But watch The Red Shoes first, for Anton swooniness.) 

Pressburger’s script directions for this scene are (as with all of them) terrific:

BARBARA is, of course, the same girl whom we have seen in nurse’s uniform in the Convent of the ‘Crown of Thorns’. She is dressed in what, in 1919, was considered a ravishing creation: rather like a badly tied sack.
CLIVE is in uniform. He is a full Brigadier now. He looks very strong and fit, far less than his forty-three years.

Yes!  Pressburger’s snarky comments on 20s fashion FTW.  I must disagree with him though.  This is my favorite outfit from the movie.