Where a term is implied on the grounds of a custom, the implication is based on the assumption that it was the intention of the parties to be bound by the custom. A custom can, of course, be excluded from an agreement by an express term to that effect. In British Crane Hire v Ipswich Plant [1975] QB 303, the contract involved the hiring of a crane. Both parties to the contract were in the same trade. The owner of a crane sought to rely on his usual terms, even though these were not actually stated at the time of contracting. The owner's terms were based on a model supplied by the trade association and were common in the trade. The court held that the owner’s standard terms and conditions were incorporated by a common trade custom.