The wheels are without doubt Romford and would say it is far more likely to be Millholme than DJH, Bit basic for DJH. The centre flangless wheels will be retained but as per the real 9f the other pairs will be replaced with flanged drivers.
However the chassis is too short front and back and the only solution would be to overlay the Airfix chassis side frames to the brass frame. But this is just guess work.
I will post the sellers notes up if I can still find them, hopefully this might spark some ideas.