Thanks Tim and Johnathan.
Technique for the camo was pretty straightforward. The base colour of mid stone was sprayed all over, then the green and brown added. I didn't mask, just got the settings on my airbrush finely controlled to keep it need and avoid overspray.
Next started hand painting the spots. I decided they would have been done the same way on the real thing so I wasn't too worried about absolute uniformity. Still it was a bit worrying halfway through, it looked very dotty! Once I was used to it though the undotted turret looked very boring.
After that it was pretty normal, filters, washes and fading before weathering.
Hope that sheds some light on it.
Thanks again for your kind comments.
Jon