We may note that in this instance Langhans was objecting to Elizabeth Scanlan's contention that the first Lincoln's Inn Fields theatre had only two proscenium doors. ("Reconstruction of the Duke's Playhouse in Lincoln's Inn Fields, 1661-1671", Theatre Notebook x, 1956, 48-50.) Langhans is by no means committed to the idea that early Restoration theatres had only two proscenium doors in all.
Keenan goes on to describe how wing entrances must have been used on the temporary stages at Whitehall and at Rutland House, as they had no forestage and thus no proscenium doors, but cuts another corner when he writes: "there is evidence to suggest that Post-Restoration operas may have followed suit.
(3) Briefly stated, Visser argues that the proscenium (forestage) walls in a Restoration theatre had 'a scenic function that supplemented that of the scenic area behind the proscenium arch', and 'as with the entrances in the classical theatre, the proscenium doors
could be particularised'.