In my previous post , I wrote about the unusual arrangement that Gooch adopted for the regulator mechanism on the first engines that were built at the new Swindon Works, where repair work started in 1843.

The first new engine to emerge from the works, in February 1846, was a member of the ‘1st Lot Goods’ named ‘Premier’. It wasn’t built completely ‘in house’, since the boiler came from an outside supplier. This was swiftly followed by ‘Great Western’, an engine with which Gooch intended to show what the Broad Gauge could do. By the standards of the time, it was a huge engine and, before putting such a radical machine into series production, Gooch introduced the ‘1st Lot Passenger’ engines, of which the first was named ‘Prince’.

Although largely forgotten nowadays, this small ‘Lot’ provided the motive power for all the main Paddington to Exeter expresses before the arrival of the large 8 foot Gooch ‘Singles’. It was these engines that established the 4½ hour schedule for these trains – a revolutionary performance for that time.

There were six engines in the Lot and each of them had minor differences from the others. The GWR initially referred to this class as the ‘Queen’ class but the RCTS booklets adopted ‘Prince’ class. A detailed description of each of the class members is given in Chapter Four of Arman’s ‘The Broad Gauge Engines of the GWR, Part Three’. The class was not perpetuated once ‘Great Western’ proved to be a success, which led on to ‘Iron Duke’ and the remarkable line of ‘8 foot Singles’. These larger engines then handled all the main expresses until the end of the broad gauge in 1892.

An early photograph of ‘Sylph’, of the Prince-class, shows the curved lever to operate the regulator, described in my previous post, in front of the near side of the firebox.

‘Sylph’ photographed c.1857 at Swindon

I decided to examine ‘Queen’ in detail. As I showed in my previous post, Queen was the subject of one of E.T.Lane’s fine drawings, which provide us with such a valuable record of the early GWR engines.

In creating a 3D model, I realised that I could draw on parts that were already in my computer design ‘parts bin’. I took the smokebox from my earlier model of a Gooch Standard Goods  , as well as the boiler, which I had to adjust in terms of length and diameter. The ‘haycock’ style of firebox came from my model of a member of the Firefly class and again needed slight enlargement to match the specification of ‘Queen’.

The only completely new parts I had to create were the wheels and the inside frames. The wheels had large numbers of fine spokes, which give a rather filigree appearance. These were easy to create by making use of the ‘circular pattern’ tool in ‘Autodesk Fusion’. Unlike the earlier ‘Firefly’ and later ‘Iron Duke’ classes, there were no outside frames, so the wheels were fully exposed, thus forming a large part of the individual character of these engines.

The inside frames were the usual type of slotted sandwich frames, so I was able to draw on the experience of having made very similar frames in the past. As usual, I extruded these by sketching over Lane’s drawing, which I imported in to 'Fusion' as a ‘canvas’. With all those ‘parts I made earlier’ to hand, I soon had a 3D model in my computer, as shown below:

My 3D model of Gooch’s ‘Queen’, with front-end regulator shaft

Note that I have incorporated the parts from my previous post ‘Gooch Regulator ’, although most of them are hidden inside the smokebox. I have not yet added Gooch’s Link Motion or its control lever – something for a later addition.

What I really like about 3D computer modelling is that I can bring together different models and compare them while viewing from various angles. When I bring this model together with my Firefly-class model, it is clear that the Prince-class represented a fairly modest enhancement of Gooch’s original ground-breaking design.

My 3D models of ‘Firefly’ (left) and ‘Queen’ class engines

The most obvious external difference is the boiler, which was 2 feet longer in the Prince class, with a modest increase in firebox dimensions. Whereas ‘Firefly’ (as originally built) had ‘gab’ gear, which provided no opportunity for expansive use of steam, ‘Queen’ was fitted with Gooch’s own form of link motion, as were all the other early products from the new Swindon Works. This motion was retro-fitted to earlier engines, as they passed through the works for major overhauls.

My 3D models of ‘Firefly’ and ‘Queen’ head-to-head’ emphasising the differences in wheelbase and boiler length.

So, my modelling has filled another gap in the development of GWR express engines, with a small class, which became obscured by the fame achieved by its successors in the ‘Iron Duke’ class.

Mike