From Milk to the Mail - The History of the Siphon G — Accurascale Skip to content
From Milk to the Mail - The History of the Siphon G

From Milk to the Mail - The History of the Siphon G

Until the latter half of the 19th century, the transportation of fresh milk by the railway was still confined to local movements, as the big population centres were still able to meet the needs for dairy provision. It was only with the huge population increases of the mid-1860s that the production of milk was forced away from the periphery of cities and into the countryside, creating the problem of being able to transport it from source to market quickly.

The ensuing rapid growth of the milk industry was entirely down to the railways providing a means of providing rapid transportation of goods to market, and the Great Western Railway was quick to realise the importance of providing specific stock to accomplish this.

Milk not only deteriorates rapidly, it is also very sensitive to movement and so any purpose built rail vehicle needed to be able to be formed into passenger trains for travelling at high speed.

Realising this, from the outset the GWR created vehicles that were very different from their standard close boarded vans, with wide gapped planks being used to ensure adequate ventilation and cooling of the milk churns, along with heavy springing to improve the ride. Experiments with doors also took place, as the GWR sought to identify the best way to load the churns onto the vans.

The early four-wheel vans that first appeared from April 1873 soon gave way to improved six-wheel vehicles, as the GWR had settled on this arrangement for its mainline coaching stock during the late 1870s and the first dedicated milk van diagrams, O.1 and O.2, appeared between mid-1889 and mid-1890; the GWR dedicating almost the entire O series of diagrams exclusively to milk traffic. These vehicles continued to be improved, but in August 1906 the first bogie milk van appeared, the diagram O.7 Siphon F (Siphon was the GWR’s telegraphic code for a milk van and the F denoted the version of vehicle).

By 1913, the Great Western Railway had reached a stage whereby the original 4w and 6w milk vans were obsolete and required replacement. A prototype 50’ bogie version, the diagram O.10 of October 1908 had proved successful and satisfied the GWR’s requirements for a versatile gangway design of milk van, leading to the creation of the Siphon G; a family of gangway bogie vans that were built between 1913 and 1955 and that would eventually total 365 vehicles.

Initially built with outside body framing and closed horizontal planking, a prototype design to diagram O.22 was built in August 1926 that featured an inside framed design, riding on 9’ American bogies (albeit still with horizontal body planking), the design proving its suitability across all areas of the GWR. In 1929, an order for 50 vehicles to diagram O.22 was placed, then cancelled (possibly due to financial constraints), then revived again in 1930 as an order for 20 vehicles to a new diagram, the O.33.

The O.33 Siphon Gs were built in four Lots, covering a period between July 1930 and May 1945 and in total 115 vans were built to this diagram. The first, and most obvious difference in the O.33’s appearance (over preceding Siphon G versions), was the introduction of vertical planking, possibly due to the wood being cheaper and easier to procure and these cost constraints were also evident elsewhere, with the first built Lots using secondhand bogies of various 9’ and 8’ 6” types, as well as used sets of Stones electric lighting. The O.33s were also 2” wider than their predecessors and were equipped with large round headed buffers, as well as a new style of gangway connector that hung from brackets, rather than the ‘scissor’ type.

As the war clouds gathered over Europe in 1938, the Government of the United Kingdom stepped up its preparations for the impact of hostilities on the civilian population, the assumption being that any bombing of the UK’s cities would produce such large numbers of casualties that the local facilities would be overwhelmed.

To counter this, a plan was put into place that would create Casualty Evacuation Trains and at a meeting of the Railway Superintendents held at Liverpool Street Station on April 4, 1939, it was agreed to create 34 semi-permanent Ambulance Trains, each to comprise two Brake Thirds and ten Vans, capable of holding a minimum of 30 stretcher cases per van. Each Railway Company was to provide a proportion of the total trains required, with the GWR being required to supply six trains.

For the Ward Cars, the GWR opted to convert 60 Siphon Gs for the six trains (numbered 326-331), as they already satisfied the Ministry of Health’s requirements for the vehicles to be electrically lit and well ventilated, but a certain amount of work was still required to seal the draughts, ensure that the vehicles were light tight and to fit the brackets and shelves necessary for the conveyance of stretchers; 42 to each van, at a total cost of £82 per vehicle.

By November 1939, one Siphon G had been removed from each of the GWR’s CETs, being replaced by a ‘Staff Car’ and by December, when the total number of CETs was reduced to 18 on standby, the GWR’s commitment had been reduced to the provision of four CETs, releasing 20 Siphon Gs back into traffic.

In July 1943, 42 Siphon Gs were required for the Overseas Ambulance Trains Nos. 32-35 and 45-46 and again a number were modified, this time to suit operation on European railways.

These modifications included the fitting of Westinghouse brakes, the removal of the handbrake gear, the addition of a water tank, end steps and handrails. In addition to the OATs, a further 12 Siphon Gs were formed into two US Army Ambulance Trains, Nos. 69 and 70.

With the cessation of hostilities, and the repatriation of the Siphon Gs to the GWR following their ambulance service, the resulting conversions back to service stock resulted in the creation of two new diagrams: O.59 and M.34.
Diagram O.59 called for the restoration of the Siphon Gs to their original body specification, with the louvres being restored. Indeed, the only discerning difference between the original O.33 and the O.59 conversion was that the roof mounted shell ventilators were retained. In total, 36 vehicles were rebuilt to this diagram, although there is some question as to whether vehicles 2979-2984 were conversions, or were built from new as O.59, given their date of construction and entry into traffic.

Diagram M.34 involved far less work to restore the remaining 31 vehicles to traffic, as they were unaltered in their appearance, remaining externally identical to their ambulance service configuration. As with the O.59, the original numbering was restored to the stock, however for the first time their designation was changed to Parcels Vans, rather than Milk Vans.

The usefulness and versatility of the Siphon G design had provided the GWR with a bogie van suited to many uses, as had originally been envisaged in 1913 and this was not lost on the British Railways Board as the era of the ’Big Four’ gave way to a nationalised railway in 1948.

Traffic levels increased as the railways recovered from the Second World War, a result of a change in societal habits and the fledgling British Railways found itself in dire need of bogie vans capable of express speed running and so it was that three new Lots of Siphon G vans, totalling 80 vehicles, were ordered and built to a new diagram, O.62, between October 1950 and October 1955. Remarkably, the new diagram was still referred to as a ‘Milk Van’, even though the Siphon G now served more in a GUV role and was very little changed from the original O.33 but for one main difference; the addition of eight sliding louvre ventilators to each body side, situated just above the solebar.

The Siphon Gs were ideally suited to parcels traffic, but the sustained growth of newspaper traffic into the early part of the nationalised British Railways era probably represented the pinnacle of this type of traffic, with the Western Region relying on its fleet of Siphons to convey newsprint. At its peak during the 1950s, 1960s and 1970s, British Railways was running more than 50 dedicated newspaper trains every weekday, with around 75 services conveying the bulky Sunday editions at the weekend, over 75% of the country’s entire weekend newspaper production.

During a typical night in the 1970-71 winter service, a total of 23 Siphon Gs were booked in dedicated Newspaper working from Paddington each weekday morning, with a further five being booked into late night overnight trains carrying various articles of mail traffic and they ran westwards, variously, to destinations as far afield as Penzance, Barnstaple Jcn, Kingswear, Gloucester, and Carmarthen, the destinations being carried on boards mounted to the bodysides of the vans.

Many of the O.33 and O.59 vans were withdrawn from traffic during the mid-to-late 1960s, but as the 1960s gave way to the 1970s and the Rail Blue TOPS era took hold, Siphon Gs were still in major use on the Western Region, with parcels and newspaper traffic being hauled by a variety of traction, including the Class 31s, Class 47s and Class 50s.

Variously classed as NNV and NMV by TOPS, and in many cases now equipped with ETH, the latter years of the 1970s saw 34 Siphon Gs rebranded with BR’s ‘Newspapers’ logo, while the remaining survivors were transferred into Departmental traffic, particularly branded as Enparts, the Western Region’s fleet of vans used for transporting spare parts for locomotives and rolling stock from Swindon to the larger Motive Power Depots. A number also found their way into use as Seat Trimming Materials Stores Vans, for use between Litchurch Lane, Derby and Swindon Works and as Newspaper traffic dwindled into obscurity during the early-1980s, leading to the final withdrawal of Siphon Gs in revenue earning service, it was these last few Departmental vehicles that soldiered on into 1985, before they too were eventually withdrawn and scrapped.

Around two dozen Siphon Gs were initially saved for preservation but that number has now dwindled, although there are nice examples surviving at the Severn Valley Railway, the Gloucestershire & Warwickshire Railway, Didcot, Quainton and Shildon, several of which formed the basis for Accurascale’s surveys of the vehicles during the research phase of the project.

The Accurascale OO/4mm scale model of these iconic vans covers the multitude of variations and changes the Siphons received during their careers. Check out our comprehensive range now available to pre-order right here.


• First inside braced Siphon G was No. 1270, built to diagram O.22 in August 1926, for use as a Milk Van, carrying milk in churns.
• Vertical planking introduced to Siphon Gs with diagram O.33
• The first O.33 Siphon G was No. 2051, built in July 1930
• 195 vehicles built to two diagrams; O.33 under the GWR and O.62 under British Railways.
• In 1938/39, the UK Government ordered the creation of Casualty Evacuation Trains (CETs) and the GWR initially converted 60 Siphon Gs as Ward Cars for this traffic.
• Later in WWII, 42 Siphon Gs found use as Ward Cars in the Overseas Ambulance Trains.
• On their return from War service, the Siphon Gs were converted back to service use as either diagram O.59 (Milk Vans) or diagram M.34 (Parcels Vans).
• 34 Siphon Gs were specifically reclassified and re-equipped as NNV Newspaper Vans under TOPS, with other reclassifications including NMV and QRV.
• Final withdrawals from service occurred in the 1982-84 period, although a number survived in Departmental service into the mid-1980s.

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