The class were introduced by George Whale in 1904 and 130 examples were built by Crewe Works up to 1907. Their introduction allowed Whale to phase out his predecessor Francis Webb's unreliable compound locomotives. They were essentially a larger version of Webb's LNWR Improved Precedent Class. As built, they were saturated, though some were later superheated. Whale's Experiment Class4-6-0 were essentially an extended version built from 1905. An Atlantictank engine version, Precursor Tank Class was also built from 1906. The Precursors were developed by Charles Bowen-Cooke into the superheated George the Fifth Class 4-4-0. The main visual difference was that the Precursors had separate splashers over each of the driving wheels while the Georges had combined splashers that covered both pairs. The LNWR reused numbers and names from withdrawn locomotives, with the result that the numbering system was completely haphazard. Starting with the first of the class 513 Precursor in 1913, were given superheaters, the process continuing until just after grouping in 1923. Most of the superheated engines were also converted from having slide valves to piston valves. This resulted in two main subclasses; saturated locomotives with cylinders, and superheated locomotives with cylinders. The LMS gave them the power classification 3P. The saturated engines were given the LMS numbers in the 5187–5266 series, though not all survived long enough to receive them. The superheated engines were given the LMS numbers 5270–5319. The LMS continued to superheat engines until 1926, these rebuilds retained their LMS number. Also, three superheated engines became saturated via boiler swaps. Withdrawals of the saturated engines started in 1927 and the last engine in as built condition was withdrawn in 1935. The four superheated engines which retained slide valves were withdrawn 1931–1936. Withdrawals of the superheated engines with piston valves began in 1935. Those not withdrawn had 20000 added to their numbers 1934–1937 to make room for Black Fives. At the end of 1939 only seven survived. Only a single example was inherited by British Railways in 1948, 25297 Sirocco, which was withdrawn in 1949. Despite being allocated the number 58010, this was never applied. None were preserved.
