When one of the UK’s largest quarrying companies grew tired of the regular breakdowns suffered by British Rail’s ageing diesel locomotives when hauling its stone trains, it turned to what then seemed a radical and unusual solution.

Foster Yeoman, a leading supplier of aggregates for roadbuilding and construction, persuaded the then nationalised monopoly that it should be allowed to buy and import four new, more reliable North American diesels. British Rail drivers would then operate them.