There is some ambiguity about the audit of not for profit entities that are not required to file under the Tier 1-4 PBE regime. This includes things like incorporated societies, charities incorporated under Charitable Trusts Act 1957 but not registered with charities commission, sports clubs etc.
While these may adopt say Tier 3 PBE reporting they may also opt for their own special purpose reporting (effectively using what they used in the previous year).
SPFR for NFPs Audits (2016 updates) addresses these kinds of jobs:
This may be accessed for a new job from client selection area or existing jobs may be updated as required to this template. 2016 style audit reports and engagement letter are included.