The class 800 was a 2-4-0 express locomotive designed by Matthew Kirtley and built in 1870 and 1871. 30 were delivered by Neilson & Co. which were numbered 800 to 829. The rest came from the Midland's own shops at Derby. Twelve of these were numbered 60 to 66 and 165 to 169, while the other six got different numbers. Locomotives of both manufacturers differed in some aspects, like the coupling rods and the reversing gear. The first ones built by Neilson had screw reversing gear with a vertical shaft that led to an accident when a driver mistakenly put his locomotive in reverse. So Neilson decided to fit another type of reversing gear to the remaining locomotives.

Their drivers measured 6 ft 8 1/2 in or 2,045 mm and the cylinders had a diameter of 17 inches and a stroke of 24 inches. The first twelve were rebuilt by Samuel W. Johnson in 1875 and 1876 when their cylinder diameter was increased to 18 inches, while the stroke remained at 24 inches. At the same time, they got a larger boiler. In 1877, eleven more were rebuilt which additionally received cylinder stroke of 26 inches. The rest was again rebuilt without increasing the stroke, since this required more changes in the running gear. From 1889, some got boilers with a pressure of 160 psi. 

They hauled the heaviest express trains of up to 230 tons and reached high average speeds. Even on the long one percent climb on the Settle-Carlisle line, they reached an average of nearly 50 mph or 80 km/h. In 1899, No. 828 was clocked with a speed of 81.8 mph or 131.6 km/h. Some say they were only surpassed by the class 3 Belpaire 4-4-0 introduced in 1900. The first ones were withdrawn in 1905, but the last of the class only disappeared in 1936.