Thanks for the support guys.
All I can say at the moment is ARRRRRRRGGGGGHHHHHHH YELLOW
Stupidly tried to do preshading before yellow:
It looks okay in the photo, but was really cruddy in reality. No amount of extra yellow was going to cover it up so start again:
Sanded off the yellow, washed it off, rescribed panel lines and tried again, looked better:
BUT the day was too hot, too humid, and the paint has dried before reaching the model, so it is very rough. So sand it smooth, just enough to lose the texture, before the third shot at a uniform yellow colour. One of my problems is poor lighting in the shed, so I don't get enough perception of the evenness of the colour density.
So, try again in a couple of days, wish me luck...