In Liverpool City Council v Irwin [1976] 2 WLR 562, a House of Lords decision, Lord Wilberforce said that the implication of terms simply on the ground of their reasonableness would be 'to extend a long, and undesirable, way beyond sound authority'. This case was concerned with the obligations of a local authority towards its tenants in a high-rise block of flats. The court was simply concerned to establish what the contract was, the parties themselves not having fully stated the terms. It was in this sense that the court was searching for what must be implied. Lord Wilberforce said further:

In my opinion such obligation should be read into the contract as the nature of the contract itself implicitly requires, no more, no less; a test in other words of necessity. The relationship accepted by the corporation is that of landlord and tenant; the tenant accepts obligations accordingly, in relation, inter alia, to the stairs, the lifts and the rubbish chutes. All these are not just facilities, or conveniences provided at discretion, they are essentials of the tenancy without which life in the dwellings, as a tenant, is not possible ... The subject-matter of the lease (high-rise blocks) and the relationship created by the tenancy demands, of its nature, some contractual obligation on the landlord.

Lord Wilberforce concluded that, since there was no obligation to maintain and repair stairs, lifts and chutes undertaken by the tenants, then the nature of the contract and the circumstances required that the obligation be placed on the landlord. On the question of standard of maintenance, Lord Wilberforce resorted again to the concept of necessity, holding that the standard must not exceed what is necessary having regard to the circumstances, i.e. an obligation to keep in reasonable repair and usability, taking into account the responsibilities of the tenants themselves. Applying this test, the House of Lords unanimously decided that the council was not in breach of its obligations with regard to the maintenance of stairs, lifts and chutes.