Exclusion of certain under-tenants

Sections 44 to 50 of this Act, shall not apply to any under-tenant where the under-tenancy has been created in breach of any covenant or agreement in writing between the landlord and his immediate tenant, or where the under-tenancy has been created under a lease existing at the date of the commencement of this Act, contrary to the wish of the landlord in that behalf, expressed in writing and delivered at the tenement within a reasonable time after the circumstances have come, or with due diligence would have come, to his knowledge. certain under-