The Shropshire and Montgomeryshire Light Railway was a railway running from Shrewsbury, England to Llanymynech, Wales, with a branch to Criggion. It was promoted by Holman Fred Stephens, better known as Colonel Stephens, proprietor of several ultra-low budget light railways. It adopted the track network of the defunct Potteries, Shrewsbury and North Wales Railway that had closed in 1880; the S&MLR opened in 1911. Running through sparsely inhabited terrain, it struggled to achieve financial stability, and following a serious deterioration of maintenance conditions, it closed to passengers in 1933, continuing with a basic goods and mineral service.

Colonel Holman Fred Stephens was a British light railway civil engineer and manager. He was engaged in engineering and building, and later managing, 16 light railways in England and Wales.