I went to get some grey paint today for my ’55. But my auto parts shop cannot do the “very old” paint mixes anymore. I was after AC131 Gris Bruyère but luckily I used the modern equivalent on the respray of my Renault 4L. So I have half a tub I am going to use as a test sample.
Here is a link to the paint codes and years but not sure it will be the same for Slough built cars.
http://www.cats-citroen.net/citroen_tractionavant/ta_colors.html