Anthony Asquith was known for his favor of adapted plays into films. With that said, it is easy to see that Asquith allowed his actors to command the space of the frame as if he were directing them on stage. He chooses to use a relatively locked off camera for the most of the film which creates the space for the actors, some of the most talented of all-time in Michael Redgrave and Edith Evans, to allow their abilities to carry the story to where it needed to go emotionally.
Asquith does open the film with the imagery of a couple going to see a play, and when the curtain is drawn we see Worthing through the binoculars of the woman, and the rounded view clears away and we enter from a play into the film version. He closes the picture with the image of the drawn curtain as well.
He also uses a tight blocking to increase the tightness of the British language. An example of this is when Gwendolen is visiting with Cecily for the first time and the two women are at each other's throats, but in the caricature British reserved manner where they stand side by side about to pop, but with very little threat of one actually doing so. This creates a heightened reality and the necessity of the language to be played in musical way in order that the comedy may reveal itself.
This is one area that Asquith showcased in the film, in each scene the actor's ability to bring the scene to life through language is on display. This is very much like the theatre, and Asquith allows it to be brought forth in this film.
