I am planning to include a dairy on my future GWR 1930s branchline. However I have some questions concerning how dairies operated. From the limited information I have found it seems that once the decision was made to move from churns to tank cars these would have been loaded at a dairy. The diary would have been supplied by various farmers in the area and their milk would be delivered to the dairy in churns. The tank cars would be picked up and included in express trains bound fir large diary processing facilities near large cities such as London. First, are these limited details correct?
Second, were the dairies located along the branchlines privately owned or were they owned by the large milk companies such as CWS, Express Dairy, West Park, etc? If privately owned were they contracted to provide milk for just one company or might they have contracts for two or more? This is important since if the former is true then only one type of tank would appear at a dairy but if the latter is the case then there might be two or more types of tanks at a dairy.
Finally once the tanks were collected and made up into express milk trains would they be a mix of different liveries or would they be all for the same company?