We’ve tried to cover the basics of what you need to know here. Bear in mind that this summary does not take the place of a thorough training in, and understanding of, the relevant legislation across your organisation.
The Equality Act
Providers of goods, facilities and services have a duty to make reasonable adjustments to provide access for disabled people. Disability is one of a number of protected characteristics within the Equality Act, and it is illegal to discriminate against anyone on the grounds of any of those characteristics. Whether an adjustment is reasonable or not will depend on considerations such as its effectiveness, its practicality for the organisation concerned, the cost, the resources of the organisation concerned and the availability of financial support.
See also A Note on the Equality Act (2010)
These don’t really apply to an existing theatre but if you have major works done then Building Regulations will apply. In particular UK Building Regulations, part “M”, give specific information relating to installing loops in rooms of certain sizes
UN Convention on the Rights of Disabled People
Article 30 – Participation in cultural life, recreation, leisure and sport – can be read here.
See also Loop systems: standards and requirements and Ampetronic’s page about standards and legislation relating to induction loops.
Having an assistive listening system doesn’t ensure compliance with the rules. Access is supposed to be on ‘not less favourable terms’ than anyone else.
This doesn’t just mean financial, although you can’t charge someone extra to use the assistance that you provide. You also need to do it in a way that doesn’t discriminate. If someone has to sit in a very restricted area to use your assistive listening system that may be seen as ‘less favourable terms’.
The adjustments you make are to be ‘reasonable adjustments’. If there are just a few seats at the back of your auditorium which aren’t covered by your assistive listening system, then it’s fine to sell them; just make it clear to anyone booking them, that those seats do not have coverage.