After numerous attempts to get the paint applied properly from the airbrush, I have finally succeeded today.The nearest colour match paint John could lay his hands on was a water based matt emulsion not designed to be sprayed with an airbrush. I tried with two different makes of acrylic thinners but struggled to get a decent flow and cover from the airbrush and was not happy with the finish. In desperation I searched the Internet for some advice and came across an article on thinners. Tamiya paints make a colour acrylic thinners called X-20A which they say will thin any water based paint. It was expensive for a small bottle but it does what it says on the tin.
Wing tanks and air brakes sprayed up and the paint match is very good. As the paint is matt finish I will give them a couple of coats of lacquer in a couple of days when the blue has hardened.