Thanks Nicholas,
I basically started by airbrushing a 50/50 mixture of Tamiya Flat White and Buff as a base, followed by a 1:1:2 ratio of Burnt Sienna, Yellow Ochre and Raw Umber oil paints, brushed on down the length of the fuselage.
The oil is then then wiped off with a paper towel until the desired colour and grain effect is reached. I then just took a dry, square paint brush and brushed some of the panels on a 90 degree angle to add variation.
Quintin