Years ago,Coke Tulip, juries were almost invariably male, aptly described as "male, middle aged, middle class, and middle minded". That was because there was a property qualification and few women qualified as owners. The sign for male jurors was probably to indicate that there were separate facilities for men and women, for when they were assembled but not deliberating. That would be in keeping with the attitude to women then. The jury would decide the case in the one room.
Incidentally, it was only in recent times that there have been separate robing rooms and facilities for women barristers; the one in the High Court is in a small, dark room, far away, in every sense, from the two very large robing rooms, each with its attendants, which the men have and which are set either side of the entrance. (When a barrister starts out, he chooses which of the two he will use and never changes to the other in the whole of his career). When the courts were built, there were no women barristers