Thankyou all for your Kind coments - Moses - I'm going to keep the camo as it is, much as like the ambush pattern, I think with all the weathering I'm doing it will end up too 'messy' if you know what I mean.
The tank is painted almost completely with Humbrol enamels -
for the rust, I ground up a rust coloured pastel and mixed it with thinners - then simply painted it on. The spare track links are brown mixed with flat black, heavily thinned to create a dead flat finish. The track sag is a series of pins holding the vinyl tracks in the correct position.
I should be finished in the next couple of nights so I'll post up the pics when I'm done.