"Lion" was ordered by the Liverpool & Manchester Railway in October 1837; one of an order of six locomotives from Todd, Kitson & Laird of Leeds. They were built according to the patents of Robert Stephenson for a six-wheel locomotive and that of John Melling, the LMR Locomotive Superintendent and included several of his patent ideas, including hollow water filled firebars; a pre-heating tank beneath the firebox into which waste steam from the safety valve could be directed; Melling's patent radial valve gear; and a coupling wheel to aid adhesion. "Lion" and her sister "Tiger" were 0-4-2 'luggage' engines for working goods trains. They had cylinders 11 x 20 inches; 5-feet driving wheels; 37 inches diameter carrying wheels; and 50psi boilers 7 feet 4 inches long and slightly oval in cross section.