The holdings to which this Part of this Act applies are any premises held under a lease, other than a mining lease, made whether before or after the commencement of this Act, and used wholly or partly for carrying on thereat any trade or business, and not being—
This Part of this Act shall not apply to any holding let to a tenant as the holder of any office, appointment or employment, from the landlord, and continuing so long as the tenant holds such office, appointment or employment, but in the case of a tenancy created after the commencement of this Act, only if the contract is in writing and expresses the purpose for which the tenancy is created.
For the purposes of this section, premises shall not be deemed to be premises used for carrying on thereat a trade or business—
In the case of premises used partly for purposes of a trade or business and partly for other purposes, this Part of this Act shall apply to improvements only if and so far as they are improvements in relation to the trade or business.