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For someone who witnessed the transition from steam power to Diesel in the 1960s, I have always been attracted to them. They are foul-smelling and the fumes they produce are not as picturesque as the steamers but they do have a certain charm and the operational advantages of not requiring turntables. In model form they are every bit as challenging to produce as a steam outline model but have considerable advantages in not having lots of vulnerable valve gear. They also generally run better, often having more pick-up points than an equivalent steam outline model.

It was with some joy that I learned that Heljan were to produce a class 31, formerly designated Brush type 2. These locos were, for many years, the maids of all work in East Anglia, hauling everything from mail and express trains to local passenger and freight workings. I followed the development story as set out by Brian Daniels on RM web where he showed the prototypes and the production models. It was soon appreciated that the version produced was the later variant with head code boxes. This made sense as these machines were very long lived and few are still around today.

My modelling era requires the earlier version with the head code discs that was later supplemented by the type modelled by Heljan. These were designated originally as class 30 being equipped with 1250hp Mirlees engines and then became class 31 when re-engined with 1470hp English Electric engines. The first 20 of the class had electro-magnetic control, designated by a red circle, which was incompatible with the remainder of the class which had electro-pneumatic controls, designated by a blue star. There were other detail differences mainly relating to the provision of footsteps in the cab front and different handrail arrangements.

I therefore determined to see if it would be possible to back-date the model to the earlier version. I looked up the relevant drawings from which it was apparent that there were only minor differences between the types. This was encouraging. I ordered the plain green version from Tower models as in the early 1960s the yellow warning panels were not applied. As an aside, I have had success in removing the yellow warning panels from other diesel models by rubbing with cotton buds dipped in isopropyl alcohol. This is time consuming but works and is also useful for removing unwanted overhead warning signs and other printed details. The loco duly arrived and I was very pleased with it. It looked just like I remembered and ran very well.

A plan for the necessary modifications was determined. The head-code boxes had to go. The footsteps moulded in the cab front required to be filled though some versions had these. A photo check of the prototype is required. The front handrails and lamp brackets were not needed as the lamp brackets were positioned higher on the early locos. It all looked quite easy. The loco is dismantled by removing four long screws each side of the bogies which allows the top to be removed. The body is handed so can only be replaced one way based on the screw housings. There are the leads for the lights and the fan unit to be disconnected which is easily done as Heljan have provided mini plugs and sockets for the various connections to the control boards. The lighting leads will not be needed but note where the fan motor one goes if you wish to keep this feature. The next job is to remove the glazing from the sides and the cab. I found that these pushed out by applying pressure to them. The cab side windows seem to lock the cab front windows in place so these need to be removed first. I also removed the cab handrails and the lamp brackets, windscreen wipers etc. and stored them along with the body-side screws.

If you are modelling an early type of Brush as I was, the small rectangular boxes which shielded the windscreen washers need to be removed though they were present on the later versions. Once again, check with prototype photos.

The head-code boxes are dealt with by prising out the front clear glazing and the lights can be levered out with the indicator blinds. This leaves the empty head-code box. If it all seems too daunting you can put it all back and no harm has been done. Before you do so, may I suggest that you paint the cab interiors and highlight the details on the driver’s control panel? My researches showed that these were a light grey with the floors a darker shade of gray. The seats were a darker shade too. The crew seats seemed to have black arm rests. However, I expect with use, the whole area probably got grubby pretty quickly even in a brand new loco.

I filled the head code boxes with layers of 60thou plasticard glued roughly to the radius of the roof. This was allowed to dry and then the gaps were filled with white plastic padding and again left to dry. Picture 1 shows the result of this first stage. The next stage was to roughly cut the box to shape which was done with a modelling saw and a mini drill fitted with a sanding attachment. This rapidly abraded the plastic to the desired roof curve. It also created a few more holes which were filled with the plastic padding and left to dry. The final shaping was done with fine files and 200 grit wet and dry paper until the desired curve had been created. I also used the plastic padding to fill the footsteps in the font of the cab and the handrail and lamp bracket holes.

The roof ventilators were central and reached a scale foot each side according to the drawings I had. To get the effect of the ribs that the front of the ventilators displayed, I shaped them from multiple layers of 40thou plasticard. As the ventilators follow the roof profile, it is perhaps the hardest part of the process to get the curves right. I found it helpful to pre-curve the plasticard using a touch of heat. Once happy with the shape, the layers were glued on and left to dry thoroughly. Final shaping was then carefully done train. The discs were painted and mounted in the holes and immediately the character of the loco changed. Lamp brackets from Laurie Griffin’s BR diesel set were fitted on the cab waist at each end and the windscreen wipers were replaced in the holes on the cab front. Picture 2 shows the loco at this stage. It also shows that there are a few more holes to fill.

As far as the underframe is concerned, the model comes with all the jumper leads for multiple working and electric train heating. These leads were removed and saved. They are easily removed from the buffer beam. The resulting holes were filled with plastic putty and painted over. It is only necessary now to re-assemble the loco on its underframe and apply weathering to choice. Note that the underframe fits in one way as the securing holes are handed. I personally feel that weathering adds to the presence of a model but readily appreciate that others like everything to be pristine. using fine wet and dry paper used wet to get a smooth overall finish. Picture 3 shows the body at this stage.

I next removed the blue stars and the overhead warning flashes from the body using cotton buds dipped in iso-propyl alcohol. Where the body bands finish was damaged in the removal process, I mixed some acrylic paint which started as a concrete colour with a touch of green and white. When dry it looks the same as the factory colour. The green was touched in with the equivalent Humbrol BR green (RC 405) which gives a very good match. The window areas of the cabs were painted an off white. Here there is an area for discussion, as some pictures show the cab area as a distinct white and others seem to indicate that they were the same colours as the body bands.

Now it is time to refit the handrails and glazing. I found the glazing sat very deep into the frames but by cutting them from the moulding, it was possible to get them to fit right in the aperture to present a flush glazed appearance. There was a prominent rubber seal around the windows which was represented in the model by a thin black line. It is most noticeable with the white cab windows as any contemporary pictures show. The cab side windows are also flush glazed in the same way noting that the door and adjacent window have an aluminium top which is moulded on the glazing to represent the opening grip. This was painted before refitting into the cab side. The glazing was secured with a drop of Canopy Glue which dries clear.

The head code discs are from the Just Like the Real Thing range. I was at a loss to work out how they could be made operational as I like to have trains with the correct head codes. I am therefore indebted to Steve Hoather who came up with the solution in a recent Gazette (Volume 18 number 9). He fitted each disc with a spigot and placed them in pre drilled holes in the cab front. So given there were two cabs to be equipped, I reckoned four open discs and four closed ones would cover all services even a royal It has still to be numbered at this stage as the transfers are awaited at the time of writing.

So there you have it. A relatively simple conversion that is quick to do. The longest time is spent waiting for things to dry. It does take some courage to start mutilating an expensive model. If you decide to follow the process to make a later disc version the cab front handrails and footsteps will not need alteration. One final improvement is to solder an extra pick up wire to the loops provided on the bogies to enable power to be collected from the centre pairs of wheels. The result is a smooth running loco which is a reminder of the interesting transition period from steam to diesel in East Anglia. Of course since both are electric powered in our small worlds, the economics of the operation need not enter into consideration.