What's your role in this? You say 'our leaseholder' but then also mention the Freholders.
As far as the Council goes you may have Planning and Building Control issues - these are completely separate to each other.
As for liabilities, well the council will go after the freeholder for enforcement. The freeholder will then go after the leaseholder for enforcement or forefieture. If the leaseholder has sub-let to a tenant, then they will have to evict and chase the tenant for compensation.
There is always scope for misinterpretation.
If my posts can be interpreted in two ways, one that makes you feel angry and one that doesn't, I meant the latter.
Everyday is an opportunity to learn something new.