My first 'stop-gap project' has turned into a pure test-case for track weathering. I was perhaps rather naive to imagine that the first colour I mixed up would be the right one. In fact its taken a number of attempts to arrive at what (for now) appears to be a satisfactory colour for the rails and sleepers.
The easiest way to describe it is that the rails are milk-chocolate and the sleepers dark cholcolate! A simple mix of Humbrol matt black (33) and orange (82) approximately 3:1 for the rails and 2:1 for the sleepers.
My initial attempts were much lighter and combined a lot more shades, but it seems that the darker colour looks a lot more realistic, and in fact the simple mixing of two colours is perfectly adequate.
Well, I'll probably change my mind tomorrow but that's it for now!