Pip,
Believe it or not that shiny image as actually a good likeness of what can be seen. It is very difficult to make out because of the high gloss glaze ... but I am 100% sure that the first letter is S. I've been through ALL the marks on Fourniers book that begin with S and I have not found any possible matches - either the mark is not quite right or the style mentioned does not match what I see. But the second letter may have a vertical line in it - like I,L,U,H,J.