Class M (Class VT before 1900)
This class is another of those groups that was used twice for widely different types of wagons. Class M was originally allocated to the tipper wagons used for harbour works construction which were classified VT and E before 1900. Very few of these wagons were actually reclassified. Some passed to contractors and the others may have passed to PWD stock. The code then became empty.
Coal Box Wagons
The M class coal box wagons of the W.A.G.R. were originally built at the request of West Australian coal companies to foster the coal bunkering trade by enabling them to bunker steamers at the ports. They were an early, partially successful, attempt at containerisation. On the surface they appear to be fairly simple group of wagons and only one official diagram was ever issued to cover the class. However, it is certain that at least two very different types of underframes were used, probably more.
In 1911 when the prototype coal box wagon was built at Midland Workshops. It was quickly followed by a batch of 99 wagons numbered in 1912. In 1913 50 more wagons were converted from a group of J class tank wagons and it seems likely that this particular group of M wagons were 16' long over headstocks.
Between 1913 and 1919 a further 147 wagons with standard 15' composite underframes were converted from wagons in classes G, J and N. Two I class replacement wagons were built at this time were standard M class wagons with 15' GB type underframes.
From 1925 onwards a further variant began to appear. This began with 22 wagons nominally converted from GB class wagons. These wagons had four steel coal boxes each of which measured 3'-9" internally. These wagons had no sides and no end planking. Clearly it is impossible to fit these coal boxes on a 15' GB type underframe and therefore these wagons must have been new wagons with 16' GC type frames. In 1929 these wagons were reclassified MA and the official MA diagram correctly shows a 16' GC type underframe. The MA group was further increased by the reconstruction of four M class wagons and the replacement of some I and IM class wagons. These are all likely to have been replacement wagons on 16' GC type underframes.
In later years the M and MA class wagons were mostly used for loco coal.
In 1948 thirty M class wagons, all of which were on G type underframes were converted to class MC. This conversion involved the removal of the sides and the fitting of a new single large cement container in the centre of the underframe. In 1953 twelve MCs were converted to class ML by modifying the container for lime traffic. The rest of the MCs were written off in 1957. The MLs survived until 1961 when they were transferred to the Public Works Department.
A final, and unrelated, class of wagons in the "M" group were the MS class sand wagons.