Resident Landlord & Tenant AST

Tenancy Types and Management

With a HMO that is normally let to 4 tenants each with a separate room only AST and the landlord moves into the property as his sole residence sharing the communal areas (livingroom, kitchen and bathroom) with the tenants. Would it have any effect on the existing AST agreement if a tenant (or possibly two) remained at the property after the landlord moved in?

All utility bills (water, electricity, gas and internet) are provided and paid for by the landlord.

Would the remaining tenants become lodgers as they now have a resident landlord or would the existing periodic AST continue unaffected with the same tenant rights as before?

I would assume the existing tenants would remain unaffected and continue as assured shorthold tenants even after the landlord has moved in?

If that is correct and the landlord grants a new tenancy (to a new tenant) after moving in to the property can the new tenants agreement also be an assured shorthold tenancy agreement or should they be resident landlord agreements?