the first years of the 20th century saw on the vr (as elsewhere in the world) a considerable increase in both the amount of traffic and the size and weight of rolling stock being hauled. in 1907, the d class was supplanted by the much larger and more powerful a class on principal mainline services. however, with their light axle load (just 12 t 10 cwt in their original form), they were quickly reassigned to the vr's branchline network, where they became a fixture for the next fifty years.