Thanks Michael, it was a variation on a theme really. The seat was primed in light grey (I always use Tamiya acrylics), then the parts that were going to show wear were painted on by fine brush using Deck Tan (you could use any whitish colour). Then I lightly airbrushed coats of Red/Brown thinned quite a bit, some thicker and darker than others (shading where required). Maskol covered the worn bits. Then once satisifed I removed the Maskol and buffed up the bits of the seat where the back and the butt go (for the obvious reaons). That basically was it. Follwed it up with fine shading, so to speak, with a
fine brush.
Cheers
Dave