In the UK, teachers accused of offences against pupils are entitled to statutory anonymity until they are charged, so he/the school would not have been required to inform parents/adult students.
As for why he was able to continue to work, it depends on the exact bail conditions that were imposed.
An absolute ban on direct/indirect contact with children is usually in relation to a specific child/children. It's possible that his bail conditions were the more common 'no unsupervised contact', which wouldn't necessarily prevent him from working in a theatre school, or attending productions. It would just mean he wouldn't be able to be alone with children without another appropriate adult in attendance. Bail conditions can also prohibit someone from entering a specific school or all schools, so it's unlikely he received that condition either.
I imagine the vast, vast majority of schools would suspend a teacher of children in these circumstances, but it's not necessarily a legal requirement - they could also consider reassigning them, or amending their duties. I haven't been able to find any details on whether he was actually teaching children or just adults, or what his exact bail conditions prevented him from doing, so it's tough to say. One article noted that he was arrested for breaking them, but doesn't say how. It also says he wasn't charged for the breach, so it's possible that it wasn't considered serious, or there wasn't enough evidence.
I understand that it's his/his wife's school, which has obviously helped them keep a lid on things. Morally reprehensible.