This cage is under the public path into the entrance of the Ape House (there is another for orangs under the exit). Pertinax can have access when the younger males are on the island, but I have never seen him there before. I think he may have had his breakfast there while his off-show cage was cleaned.
It looks grimmer than it really is and is usually only used for short periods, although Kumbuka used to watch the world going by for half a day at a time while separated from the others. With the new fence up, there's less of a view for them now.
@Gigit Yes, I don't like that fence. He was looking at the camera because it had suddenly appeared over the top of it. I agree that the cage is not attractive in any way, but it is useful because it lets the keepers give him the choice of a breath of fresh air away from the others.