Qoute="they decided to end the plaay, as they could no longer gaurantee the safety of the audience"

Suerly it is the polices job to keep law and order and protect the public from rioting mobs? not theatre box office ticket stall staff.

The police spend thousands on crowd control at football matches, Notting Hill Carnival, and demonstrations by Hunt supporters, and anti hunt people.

So why should it be left to theatre staff to sort out riots at a theatre?

This sort of incident is waht riot police are trained for, and experineced at, [Miners Strike, Poll Tax riots etc].
Why werent they deployed?