Landlord and Tenant Act 1985, s 18 (LTA 1985) defines a service charge as 'an amount payable by a tenant of a [dwelling] as part of or in addition to the rent— • which is payable, directly or indirectly, for services, repairs, maintenance, improvements or insurance or the landlord's costs of management, and • the whole or part of which varies or may vary according to the relevant costs.' LTA 1985, s 30 provides that a landlord means