These 6-wheeled tank wagons were designed to run at express train speeds, ensuring that the fresh milk was conveyed swiftly to Britains major cities. Often a daily round trip was operated from country dairy to London and back. Many specific milk trains were operated, from a couple of tank wagons and a suitable guards brake van on country branch lines to heavily loaded trains hauled on mainlines by powerful express passenger engines. These milk tanks also ran as 'tail traffic' on branch lines and local passenger trains, using scheduled trains ensured speedy delivery and return of these wagons. Moelling this type of operation adds interesting traffic for your layout, as your loacl passenger trains' engine shunts the milk wagons before the train continues its' journey.
'Tail Traffic' is the term railwaymen use to describe non-passenger vehicles (eg. mail and parcels vans) attached to passenger trains. Moving goods by scheduled passenger trains was much faster and more predictable than waiting for slow goods trains, so was ideal for highly perishable goods like milk and premium rates wre charged for this service. The six-wheel milk tank was specifically designed to travel safely at express train speeds, swiftly delivering milk to major cities.