Build : Last updated on 14/01/2026

This section aims to tell the story of building a modern steam locomotive. You can read the build diary by following this link. The Build Diary provides a month by month account of the building of Hengist.

Current Situation

1. Frame Assembly

Frame assembly is nearing completion and the main remaining task is to finish the frame bolting. Frames were assembled in British Railways days by using cold fitted rivets. Have a look at this page for an explanation of why we used fitted bolts. The main area of difficulty has been the fitting of the new dragbox. Here we have to bolt through 3 components - the dragbox, the frame extensions and the hind beam gussets. We are close to finishing this work. The areas requiring bolting are the dragbox, bogie pivot, the brake hanger brackets and the pony truck centring pin.

A final riveting session will be required on the horizontal stretcher in front of the smokebox saddle. This can only be completed once the cylinders have been fitted. We will need to remove the smokebox saddle in order to drill the fastening holes in the cylinders. Once the cylinders are firmly fastened, we can complete the riveting. Riveting in front of the smokebox saddle differed in that these were hot rivets.

2. Main Cylinders

The manufacture of the pattern and the casting of the main cylinders is a long term job and we reckon that it will take 3 to 4 years to manufacture the complex pattern. Work is well underway on this job and our pattern maker, Tony, has provided a comprehensive step by step account of how you make a complex pattern, as is required for the cylinder casting. You can follow progress by clicking the link below or by following this link. All CAD design work is complete and the motion cylinder pattern is complete. Work is in progress on the valve cylinder pattern and the main flange that allows the cylinders to be bolted to the frames. The complex part of the job is creating the "cores" for the internal air spaces and the necessary transfer passages and unions. We have a sponsor for the casting of the cylinders.

New hind cylinder covers have been cast and machined. They have been modified to provide more support to the front of the slidebars - you can find the full story on this page. We had 2 front covers in stock which were sourced in the early days of the project. One has failed Non Destructive Testing and has been scrapped. A replacement casting is currently being manufactured. Once that has been cast, both covers will be sent for machining.

We have 4 cylinder drain cock bodies in stock although these were procured in early days. They will need full non destructive testing to confirm the material before they can be machined. We will need to procure one more body for the fifth drain cock we need. Quotations are being sought for the pressure relief valves to be fitted at each end of the cylinders.

3. Front Bogie

The front bogie is in teh final stages of construction. The bogie was assembled and displayed at the 2025 Greatest Gathering in Derby. We have now partly dismantled the bogie to check the clearances between the axleboxes on the wheelsets and the axlebox guides fitted to the frames. No further work is required so the axlebox guide liners are being fitted to the axlebox guides.

We have now found a supplier who can produce the rectangular section side control springs. In order to fully understand the spring material, we have conducted material checks on 70000 Britannia, 70013 Oliver Cromwell and 71000 Duke of Gloucester during Autumn 2025. We expect to place an order soon. You can follow the bogie build below.

4. Coupled Wheels

Procurement is well under way for the coupled wheel sets. Unlike the bogie roller bearings which were available 'off-the-shelf', the coupled wheel bearings are to special order. An order was placed on Timken UK in the summer of 2025 and the 6 bearings were delivered in December 2025. Order have been placed for the axles and tyres and we expect to have these in stock for spring 2026. The cannon axleboxes, like the bogie, are a Timken design so we have had to reverse engineer the Timken drawings. Our drawings are in the final checking stage and we expect to issue a Request for Quotation shortly. We are also seeking the material for the crank pins which need to be pressed into the wheels. This is axle grade material.

5. Trailing Truck or Pony Truck

The next task in the build plan will be to manufacture the trailing truck. With the front bogie and trailing truck fitted to the frames, we have the ability to more easily move the frames, if required. The trailing or delta truck for the lot 242 Clans follows the same design of 71000 Duke of Gloucester in having a coil sprung truck. Keith Collier who was the Chief Engineer for 71000 (and who worked at Crewe Works) has said that 71000 was one of the best riding locomotives he travelled on. Detailed design work is in progress

6. Tender

The tender can be developed in parallel with the locomotive so we are looking at policy decisions for the tender. You can see some of our thoughts by following the link below. A number of small components for the tender have been constructed.

7. Boiler

The boiler is a long lead item and we already have had discussions with potential suppliers. Our current plan is for an all welded boiler with a all steel firebox. On the BR strandards, the inner firebox was copper and the outer was steel. Bulleid Pacific locomotives had all steel fireboxes and have a long service life, providing water treatment is applied rigorously. There will be a need for an increased gap between the inner firebox and the outer firebox which will mean that 72010 will have a different outer envelope to the original Clans. There is a considerable amount of design work required before we can consider placing an order for manufacture. The smokebox and cab have already been built to provide a showcase for the project.

Detailed Information

Below, you can find links to more detailed information on particular components or issues. We hope you find them interesting! Please click on the links (if available) below to view the articles. If the link isn't available, we're currently working on it and will have information on this shortly.