Shortly before the turn of the century, Henry Ivatt had the task of developing a new locomotive for the increasing loads of the most important express trains. He had to measure himself against the singles from his predecessor Patrick Stirling, who were still considered excellent and very fast, but no longer powerful enough. Now this was the first use of the 4-4-2 wheel arrangement in Great Britain, which originally came from the USA and was known there as “Atlantic”. While the Atlantic was developed in the US from the 4-4-0 “American” to allow for a larger firebox and smoother running, in the UK it was a 4-2-2 “Single” with an extra coupled axle. 

The class also represented a departure from British tradition in other respects, most notably with its outside cylinders. The class was initially only named after the first one built with the number 990 and later got the designation C1. To distinguish them from the larger boiler design of 1902, the locomotives are generally known simply as “C1 (small boiler)” or “Small Atlantics”. Because of the American influence, they were also nicknamed “Klondykes” after the Klondike Gold Rush. A single example, number 271, was built in 1902 with four small simple acting cylinders.

In total, 22 were built by 1903. The locomotives easily reached 90 mph, which proved difficult in everyday use on lines such as between London and Doncaster. At some speeds, it was often found that the cylinders were too small to utilize the boiler's output. This led to unfavorable valve gear settings during operation, which led to high steam consumption.

In 1909, number 988 was the only one equipped with a Schmidt patent superheater. The boiler pressure was reduced from 175 to 160 psi and in return the cylinder diameter was increased from 19 to 20 inches. From 1914 all other class members were rebuilt with the Robinson superheater. From 1923, they came to the LNER as class C2. Their withdrawals began as early as 1935 and lasted until 1946. Today only number 990, which was built first, still exists, which bears the name “Henry Oakley” after the former managing director of the Great Northern.