Actually. it did start during the Great War. I got Osprey book on the soldiers, but no detailed information on how they fought. It seems that to make the soldiers, we could use existing World War One figures of British soldiers and World War Two shoulder boards available from Eduard in photoetch, and Russian weapons sets from Miniart. Anybody make any attempts so far?
Vast quantities of British surplus uniforms were sent to Russia after the Armistice, along with kit and equipment, but it is debatable how much made it through the chaotic White supply systems to the troops on the front line. There is a figure in the Osprey "White Armies" book in complete British kit (including Brodie helmet) with imperial full dress shoulderboards, which must have a source somewhere, but that cannot have been too common. More likely would be a mix - a British tunic, with russian insignia, over Imperial trousers and boots; or the Russian gymnastierka top as shown above, over British trousers, ankle boots and puttees. Steel helmets of any type would have been rare; most would have worn Russian peaked caps also as in the picture above, but by this time mostly with their stiffening wires removed.