Glamour figure he may be, brilliant sometimes he could be on the field, it was the barely perceptible action that often kept him apart.

Then, suddenly, there was a barely perceptible hush.

All of a sudden, there is a barely perceptible change: critical party mass.

There was a barely perceptible pause, and then the meeting continued as if nobody had said anything untoward.

As in so many films, its barely perceptible movement conveys exactly what her character is thinking.