Wednesday 25 November 2020

16mm Wren and history

This Kerr, Stuart Wren model is one which could appear in ‘A history of the Industrial Revolution in One Hundred Objects’ It is a machine which summarises the years 1880 to 1930.

16mm Wrightscale Wren in black livery

We were thinking about objects which reflect the turn of the 20th to 21st century and there are none better than the autonomous vehicle. The technology was waiting for electrically powered cars (around since the 19th century but needing a fair degree of refinement). It also needed good roads, vast infrastructure and most of all a well developed and integrated artificial intelligence. A model would be interesting, future implications more so. Is AI (autonomous intelligence) the way forward? Are we creating divinities or monsters? A novel we have been reading explores the questions that the autonomous car raises. It is enjoyable with characters you like and loathe and some absorbing action. You’d like it too:

Collision by Francis Morrow available from Amazon e-books.

Meanwhile, back in the 19th century, we have a steam locomotive.

As an object, the Wren shows the development of British industry, decade by decade.In 1880, Glasgow was a powerhouse of trade and manufacture. These days, the city is dismissed as a branch office but at the time, Glasgow entrepreneurs were finding work for everyone else in the country.

Wrightscale Wren pushes  small freight wagons,

The company started in 1881 as James Kerr, acting as agents for English factories. In 1883 the name was changed to Kerr, Stuart & Co. In 1892, the company purchased Hartley, Arnoux and Fanning and moved to Stoke. The company they had bought provided railway locomotives and trams. The later they sold on, but kept the railway business. In short, here was a vigorous new interloper buying and breaking up an established company. We hear of modern Hedge Funds and Trusts doing this, and so Kerr, Stuart were nothing if not modern.

Hartley Arnoux and Fanning were already manufacturing standard gauge locomotives, known since the early 19th century but under Kerr, Stuart they expanded their narrow gauge division. Although narrow gauge railways were known for moving loads for short distances, Kerr Stuart increased the number and variety of locomotives available. Yes, innovators such as Spooner and Fairlie in Wales and Decauville in France had demonstrated the vast possibilities of the new technology, but in small numbers. Improvements in material – special steel, presses, riveting etc - had certainly helped. In the early days, experiment threw up delightful curiosities such as vertical boilers. Decauville, Mallet, Prosper Péchot and Charles Bourdon refined the technology, but in small numbers. Companies such as Kerr, Stuart took narrow gauge locomotives to a vast new public. Only a few Mallets were ever built; in contrast, more than 160 Wrens alone.  Such machines evolved from curiosities to valuable prime movers.

The Decauville Company introduced narrow gauge railways which were worked by human power. Illustration couresy J. Hawkesworth,

By 1903, Kerr Stuart were offering a tiny locomotive – the 0-4-0 Buya class, named after the first customer to place an order. Here we come to another significant innovation. Kerr Stuart did not wait for orders. This was the safe and accepted procedure at the time, but customers can’t usually successfully describe what they really want.  As Henry Ford used to say of motor manufacture: Don’t ask the customer what he wants. He’d say ‘faster horses’ .

No. It was better to have a few locomotives in stock for the customer to examine and see what was wanted. The company would start a batch, usually of six. A few examples were held back from completion and then customised in accordance with the buyer’s requirements.

The development of the Wren bears this out. In 1905, Works No 888 was produced, at 4.2 tons in steam, a slightly larger version of the   tiny Buya. This design was known as the ‘old-type’ Wren, squat and with other distinguishing features. The cylinders are horizontal, it lacks draincocks and as a result blows steam continuously. The very first examples ran on cast steel wheels. This particular feature was soon modified. Later these old types were modernised, with cast-iron centres and steel tyres which could be replaced.

Works photograph of new-type Wren courtesy Armley Museum

In 1915, the first ‘new-type’ was introduced although even after this date the company was asked for the original design. Old types could be younger than the new (I hope you’re keeping up!) The overall height of the locomotive was increased to just over 7’ above the rail (so still quite Wren-like) and the boiler was raised giving an airy feel to the engine. Airy is the word I’d use as daylight is just about visible under the boiler. Very importantly for the crew, the cylinders were angled and drain cocks were fitted, reducing the constant cloud of steam which, as physicists would remind us, is not only wet and opaque but also HOT.

The majority of Wrens follow this ‘new-type’ design, including the best loved of all surviving examples. In 1922, 27 Wrens were ordered by RW Neal and Co for use building a sewer at Barkingside in Essex. In 1929, six of these were resold to Devon County Council for use in a quarry for road-stone. These were typical, non-glamorous uses for the Wren prototypes. Pixie went on to for use at the Leighton Buzzard sand workings, and survived. The story of Peter Pan is similar.

Another reason for the popularity of the design was that it could be adapted. There are oil-burning and wood-fired versions, tramway designs and Sherpa types for tackling steep slopes.

The most interesting variations are the gauges once offered. Between 1903 and 1914, the Wren was supplied to run on a variety of gauges; indeed, the customer could, within reason, specify. Works number 911 of 1906 was built to run on 1’8” (50cm) gauge while number 1041 of 1908 ran on 915mm gauge. The very narrow gauge version had outside frames. As metre gauge Kerr Stuart models were available, the customer would look at those models for anything approaching that gauge.


By 1915-16, most Wren new-builds went over to 2’/60cm gauge. The Wren reflects the history of the 20th century and was changed for ever

The events of 1914-18 required a system of military narrow gauge which could supply the vast armies fielded by Allies and Central Powers.

Thanks to Prosper Péchot and his circle, the French Army had a sophisticated design using sturdy prefabricated track, easy to lay, quick to remove on which sturdy locomotives and trains could run. Péchot had determined that 60cm was the best gauge.

The Germans spotted this promising new system and copied it, down to the design of wagons and the 60cm gauge. No doubt this was a compliment, but of course Péchot did not see it this way. In spite of their suspicion of foreign design in general and the metric system in particular, the British were forced to admit that the foreigners had a good idea and copied it for themselves.

British narrow gauge went over to 60cm during and after the War. Thus most orders for Wrens tended to be for 60cm/2’. This is true of the Wrightscale 16mm Wren. It runs on 32mm track, a scale 2’


The Kerr Stuart Wren story does not end here. The company survived the War and seemed to be in robust health. However in 1930, it was wound up. This is a story in itself. Money had been diverted to a mysterious subsidiary and suddenly there was nothing in the current account to meet day-to-day expenses. The Company Secretary went quiet but suddenly committed suicide, leaving a pile of charred paper in the office grate.

It was a sad end to an organisation with valuable intellectual property. The designs, spares and goodwill were sold to the Hunslet company of Leeds and Kerr Stuart products, rebadged, continued to be in demand. Although Hunslet has also gone,  Wrens are still in production at Statfold Barn Engineering.

If you wanted the best and worst of British railway history in miniature, look to this model.