I tried posting this on the main forum in the 42x thread but it seems to have vanished, so better luck here. I spent an evening adding a few tweaks to the Hornby 42xx:

Nothing very clever: new smokebox dart (Eileen's Emporium), the old handrails levered out with a knife-blade and then re-positioned to stand out from the body, the cab roof removed to add figures and a little paint to the interior walls, and then a dose of weathering. I painted the smokebox, running plate and tank tops matt black, then went over the other bits with a mix of Tensochrom oil and kerosene active surface agents, followed by Tamiya weathering powders while the Tensochrom was still tacky. Finally, class H headlamps and a Spratt and Winkle coupling bar, and off she goes.

I'm pretty happy with this model - I can understand the arguments against it in terms of detail versus price, but in terms of what it is, there's really not much to fault. Adding the smokebox dart took five minutes, but I suppose I was lucky to have one in my spares box - would they have been better off doing that as a separate detail, rather than - say - the lamp irons? It runs tremendously well, and on my layout at least, there's no question over its haulage capabilities. I have another 42xx in green and look forward to the 52/72xx models when they become more readily available.

cheers!