My main intervention was to lengthen each of the bodies by one compartment; an old suburban composite coach was slaughtered for the purpose. This seemed to have the exact same profile as the other coaches but in reality the center coach has a slightly different profile from the driving bodies and the composite. So on the center coach the fit isn't perfect. To minimise the number of cuts, back ends were exchanged between cars. This operation was finished surprisingly quickly, not more than two afternoon sessions including the roofs. Two of the discarded buffers are installed as centre buffers on the center coach, as per the prototype.
The lenghy work was the detaling and painting that followed.
Apart from many scratch-built parts, I installed replacement driving wheels from Tony's Store, a dummy driving bogie and buffers from the Hornby Brighton Belle, Bachmann Bulleid bogies (center coach still to be done), headcode stencils from Roxey Mouldings. The green is Humbrol Rail color Southern Green acrylic (but I had a hell of time spraying it, the result has an orange skin, this is the best I could do with it). Decals are self-printed. The lamp is replaced by a led but I will reduce the resistor as the present light seems a bit dim (any one know of a photo where you can see how bright it should shine?) New interiors were built in card and detailed with the old Peco Kitmaster card kit (scans of these abound on the web) -- the colors aren't precisely right but it looks nice and I can live with it. Flush glazing is from South-Eastern Finecast; fitted slightly un-flush because as intended it made the bodies look more like the post-war EMU generation, too smooth for the pre-war types. This was done by inserting strips of thin card between the edges of the glazing and the coach body, so that the glass surface on the outside recedes a little. The door and front windows have just plain flat plastic glass.
Obviously the model is still a mixture of types, as much as the original Triang was. To have some sort of guidance I took the South-Eastern units of 1925-26, no's 1496-1524 as reference, as they seemed to come closest in appearance. Several of these served as de-icing units after their passenger lives. The main differences are the number of compartments (8 not 6) and the tumblehome which is more pronounced on the model than on the real units (making the model more elegant than the real thing, in my opinion).
I left the motor in place since I find it a piece of historic mechanics in its own right, with a charming way of running that suits the image you want for these antique units. I suspected however the magnet had lost some its force; I don't have one of those re-magnetising machines but attaching a couple of strong neodynium cube magnets for a while (bought cheaply from China) had a noticeable positive effect too. I expect I will have to repeat this every once in a while. The running direction had to be reversed to comply with the modern standard, which was more work than you might expect (and involved drilling the hole in the bogie body visible in the picture, to insulate the pick-up from the body).