Some ten locomotives, the final series of LB&SCR main line goods engines, were built at Brighton between March and September 1906. The first five had 17½in x 26in cylinders whilst the second five were initially provided with ones of 18in x 26in, though these were later reduced to the same as the first five locomotives' cylinders. Originally provided with 3,112 gallon tenders, they were later fitted with smaller ones from the B2 class as those locomotives were rebuilt to class B2x. From 1917 the R J Billinton style chimnies were replaced with Marsh's larger version and four locomotives were fitted with L Billinton's double domed boiler during 1920. As was frequently the case with small classes, they didn't last as long as their contemporaries in the larger classes, probably due to the higher number of "good" engines in the larger classes, and were considerably out-lived by the C2x class, though eight survived into early British Railways ownership. The C3 was known for running hot at speed, which also placed it at a disadvantage when compared with the C2x which could happily handle any heavy excursion train.

Many of the class spent much of their days shedded at Horsham. One locomotive, N°304, received a saddled and extended smokebox though there were rumours that she had been rebuilt with a circular smokebox, to be classified as C3x, but this did not happen and there was no C3x class. N°304 was the first of the class to be withdrawn.