I have something exciting to add to this. I think I now have Father and son versions. My latest (Father) appears to be in canary flint. The metal is full of bubbles and the pressing isn't as nicely finished as my yellow green one. AND the canary flint one is marked PATENT under the spout and it has a pressed handle without a finger hole. My guess would be that this was a very early one and before the catalogue. There is a bit of damage on the handle but I had to have it.