The GNR class J13 (LNER class J52) saddle tank engines appeared in 1897, a development by Henry Ivatt of the existing Stirling-designed J14 (LNER class J53). The new engines carried a larger diamater domed boiler (in place of design) which proved a more more efficient boiler than the previous domeless Stirling boiler, but was the same length. This allowed J14 class locomotives to be rebuilt, hence although only 85 new J13s were built LNER class J52 peaked at 136 locomotives in the early 1930s, just one of the J14s not being rebuilt.
The class became a common sight in North London, covering the North London Line which linked the mainline railways around the north of London, pilot and shunting duties at Kings Cross, and in numerous marshalling yards up and down the country.
Approaching the end of their nominal 40-years working lives withdraw was planned to commence in the late 1930s, but was delayed by the outbreak of war and 132 locomotives were passed to British railways ownership. The arrival of new diesel shunting engines saw withdrawals resume through the 1950s, with just three left at the end of 1959.
In 1959 with just a few of these classic Great Northern locomotives remaining in May 1959 68846 was purchased privately by Captain Bill Smith, becoming the first privately preserved ex-British Railways steam locomotive.
(For context, in March 1959 the Lewes and East Grinstead Railway Preservation Society had been formed, soon to adopt the title Bluebell Railway Preservation Society)
68846 was soon repainted into the beautiful pre-grouping GNR green livery with her original number 1247 restored this engine has gone on to a long and historic career in preservation and is now a part of the national collection based at the National railway Museum, York.