My 4 plank open has now been painted, the colour I originally bought was just too orangey (Humbrol Satin 132) despite the colour on the tin lid, so a second coat was applied this time adding Humbrol Matt 70 to it in a ratio of about 3 x132 to 1 x 70 to obtain the "warm", "light", "dark" red that GWR wagons are reported to have been painted in the later years of the 19th Century.
Whilst I had the paint pots out I also applied a little weathering to the 2 Iron Mink that I had already completed, for this a little Precision Paints Track Colour was dry brushed around the lower sides and ends and the solebars, springs, axleboxes, etc. This weathering was built up in a couple of applications to hopefully give a subtle effect.
Photos of the 3 wagons can be seen below. The 4 plank open I intend to fit with the cast plates (rather than painted lettering) that were fitted to the example I have copied. I did try printing the "G.W.R" and "632" on a dark grey background on matt photo paper on the inkjet printer - not completely satisfied with the result as the lettering is only about 3pt font high and is pretty well invisible. I will now try scratching the lettering onto a piece of white styrene sheet that has been painted grey to see if that is anymore to my liking (so as yet the red wagon shows no sign of company ownership).