It was quite common for this class of engine to pull a typical Midland express weighing 200 and 250 long tons (203 and 254 t; 224 and 280 short tons) which suited the Class 115 perfectly. Given a dry rail they could maintain a tight schedule with 350 long tons (356 t; 392 short tons). Speeds up to 90 mph were not uncommon and the sight of their whirring huge driving wheels earned them the nickname "Spinners". Thanks to the Midland's practice of building low powered locomotives and relying on double-heading to cope with heavier trains many enjoyed working lives of up to 30 years. They made ideal pilot engines for the later Johnson/Deeley 4-4-0 classes.
In the Midland Railway 1907 renumbering scheme, they were assigned numbers 670–684. During World War I most were placed in store but, surprisingly, pressed into service afterwards as pilots on the Nottingham to Londoncoal trains. Twelve locomotives survived to the 1923 grouping, keeping their Midland Railway numbers in London, Midland and Scottish Railway (LMS) service. Nevertheless, by 1927 only three of the class remained, with the last engine, 673 (formerly 118) being withdrawn in 1928 and preserved.