The small engine policy served the Midland well when its network was confined to the English Midlands, which is largely free of steep gradients. As the company expanded into other parts of Britain the policy's downsides began to cause problems. The company's own main line to Scotland (the Settle-Carlisle Line) and the Somerset and Dorset Joint Railway (where the Midland was responsible for providing locomotives) were renowned for their steep gradients and the company's locomotive stock proved badly suited to the task. Nonetheless the small engine policy remained and double-heading or banking was used to make up for the shortfall in power. The policy also greatly reduced capacity on the Midland's network as not only were there more (but smaller) trains than there would have been on another railway but further capacity was taken up by the need to accommodate light engines that had been used for piloting or banking duties that were returning to their depots. The small engine policy was a contributing factor to two fatal accidents on the Settle-Carlisle Line, at Hawes Junction and Ais Gill. In the former case it was due to excessive light-engine movements and in the latter due to a train stalling on the main line due to a lack of power.