With the expansion of commerce, ships began to engage upon regular liner trades, and also ventured further and wider in seeking cargoes. Hence the development of insurances on ship and freight, expressed not for a voyage, but for a period of time-usually 12 months. The question then arose-over what period could particular average losses occurring during the currency of a time policy be aggregated in order to ascertain whether the memorandum percentage had been attained? It was not until Stewart v Merchants’ Marine Insurance Co2 that this question was answered. The Court of Appeal held that, although the policy was for a period of time, the aggregation of losses, for the purpose of ascertaining whether the stipulated percentage had been attained, should be limited, as in the case of a voyage policy, to those which had been sustained in the course of a round voyage. More or less simultaneously, the practice grew up of including a ‘‘voyage clause’’ in policies of insurance for time, whereby (as in the 1903 Time Clauses), ‘‘the warranty and conditions as to average under three per cent to be applicable to each voyage as if separately insured’’, and there followed detailed provisions as to how each voyage should be made up.