Finally I've got round to applying the final weathering with pigments. It's taken a while due to other more pressing matters and yet again a massive dip in my modelling mojo!
So first I started by applying some VMS pigments to the tracks then added some worn metal effects with graphite powder and a pencil. The lower hull was then lightly weathered with pigments before fitting the tracks in place. The rest of the model has again been finished with a light application of pigments. Just a little bit more needs to be done before I can sort out a small base for it.