Complex sentence: Previously everyone working in the theatre was allowed access to the latter Order however at some point in the early 19th century membership was restricted so that only people who actually appeared on stage could become members, thus excluding backstage staff.
Split into simpler sentences: Previously everyone working in the theatre was allowed access to the latter Order. However, at some point in the early 19th century membership was restricted so that only people who actually appeared on stage could become members, thus excluding backstage staff.