sorry, I'm not sure if we're at cross purposes Ivo - I wasn't implying it was FROM Bristol - simply that I thought the colour was what we call Bristol blue (might have been made anywhere - although doubt you'll get a result on that question). However, this might just be a difference in name for the same colour - for all I know maybe people like yourself (on the Continent), use the word cobalt, whereas us plebs in the UK use the word Bristol.
And the answer to my question regarding the pontil, is............