A brief note: the transfer from the word document I typed to a pdf file for inclusion here has caused a little scrambling of the details, but I think it should still be intelligible. Apologies.
This list is also not wholly complete, as there was at least one manufacturer of the Mills in Northern Ireland that is not included. However, it is the only list of manufacturers that I have ever come across, & was kindly given to me by a FrenchMills enthusiast on the Somme about twenty years ago.