Thanks Tim, to my mind it is looking better and better as I add things !
As part of the renovation, I am going through the brakes, because to be honest, that is what started the whole process. I have found that the whole system is "gummed up" with a kind of "jelly"
This isn't the sort of crustiness that you get with a slow brake fluid leak that you occasionally find under a dust cap, but a glutinous mass everywhere !
I had the brakes "professionally" rebuilt before the car came to France and there is something not right. They worked well for a while but after some time of lay-up they have blocked. It doesn't feel like moisture because there is no corrosion or seal damage, it feels more like an incompatibility of brake fluids

I am not too concerned because I am stripping and cleaning EVERYTHING, flushing all the brake lines and replacing most anyway. Then refilling with a known, quality brand of brake fluid - I am not tempted by silicone in this instance
Has anyone come across this issue ?
Anyway, enough of that , here is a photo of a cleaned up master cylindre !