The working of the line then commenced, and the results were such as to surprise even the most sanguine of its projectors. The traffic upon which they had formed their estimates of profit proved to be small in comparison with that which flowed in upon them which they had never dreamt of. Thus, what the company had principally relied upon for their receipts was the carriage of coals for land sale at the stations along the line, whereas the haulage of coals to the seaports for exportation to the London market was not contemplated as possible. When the bill was before Parliament, Mr. Lambton (afterwards Earl of Durham) succeeded in getting a clause inserted, limiting the charge for the haulage of all coal to Stockton-on-Tees for the purpose of shipment to ½d. per ton per mile; whereas a rate of 4d. per ton was allowed to be taken for all coals led upon the railway for land sale. Mr. Lambton’s object in enforcing the low rate of ½d. was to protect his own trade in coal exported from Sunderland and the northern ports. He believed, in common with everybody else, that the ½d. rate would effectually secure him against competition on the part of the Company; for it was not considered possible to lead coals at that price, and the proprietors of the railway themselves considered that such a rate would be utterly ruinous. The projectors never contemplated sending more than 10,000 tons a year to Stockton, and those only for shipment as ballast; they looked for their profits almost exclusively to the land sale. The result, however, was as surprising to them as it must have been to Mr. Lambton. The ½d. rate which was forced upon them, instead of being ruinous, proved the vital element in the success of the railway. In the course of a few years, the annual shipment of coal, led by the Stockton and Darlington Railway to Stockton and Middlesborough, was more than 500,000 tons; and it has since far exceeded this amount. Instead of being, as anticipated, a subordinate branch of traffic, it proved, in fact, the main traffic, while the land sale was merely subsidiary.