indentThe Great Western had been notable users of Steam railmotors in the early part of the century but they had all gone by the Second World War.   To replace them, ordinary locos fitted with "Auto gear" and coaches with a driver's compartment were used (the famous "auto coaches" - often themselves conversions from steam railmotors), until in 1936, the GWR introduced the first diesel railcars for both branch and main line use.  They were successful but when more came to be made during the early days of the war a more practical, if utilitarian shape with angled corners was used, as opposed to the streamlined 30s styling of the originals.  
indentThis is the diagram chosen by Lima for their now quite elderly 4mm scale model.  However the basic moulding is pretty accurate and with a few minor modifications and some detailing a useful model with unique character can be cheaply provided.
indentThe originals did not have buffers and normal coupling gear but the last two streamlined versions and all the later angular ones did and were rated for a tail load of 60 tons.  This is useful on a model like this in that the whole unit - if the headshunt is made long enough to enable the railcar to clear the points - can be used to do some shunting so adding to the operating interest.  Typical tail loads included cattle vans, horse boxes, perhaps an extra coach (or even two, rarely), or perishable goods such as locally grown fruit, cheese or milk.  

indentOn most layouts you have to bring such traffic on with the railcar's first appearance and can only add an out-going load during its last visit because there's nowhere to uncouple it.  On this layout however, because the hidden sidings are reversed into by outgoing trains, a suitably-placed uncoupler can relieve the railcar of its tail-load between visits so making operation all the more interesting!