GWR Siphon

The GWR Siphon was a series of enclosed milk churn transport wagons built by the Great Western Railway and continued by British Railways.

The GWR, being a railway system which served the rural and highly agricultural West of England and South Wales, had a resultant large requirement to transport milk in volume. Post grouping in 1923, of the 282 million gallons of milk transported by rail by all four national railways companies, the GWR had the largest share of milk traffic, followed by the LMS, the Southern particularly from the Somerset and Dorset Railway, and finally the LNER from East Anglia.

Often, the milk was delivered direct from the farmer to the local railway station in milk churns. So to remove the need for moving unprocessed milk from one container to another, and hence potential cross contamination or need for the GWR to install hygienic washing facilities, the decision was taken to transport the milk churns.

The first Siphons - named after the GWR's Telegraphic code for a milk wagon - appeared from Swindon Works in the 1870s, later given diagram O.1. 75 wagons were built to this diagram under lot numbers 180 and 217, able to carry 17 gallon milk churns stacked two high. This first design was removed from traffic by the outbreak of World War I.

These early Siphons set the key design precedents for their later larger successors:

The first design, like many later Siphons, was constructed on recycled chassis from earlier passenger carriage designs, and hence all Siphon variants were not designated goods wagons, but carriages.

The Siphon C was a development introduced from 1906. This had more enclosure, but also bigger vents at higher level. The Siphon E was the first vehicle to use a tri-axle arrangement, introduced from post World War I they were withdrawn from the late 1930s as train speeds increased.

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