The Pannonia Steam Flour Mills was identified from this newspaper article (see no.7) supplied by Paul Cannon:-
'The United States Miller and the Milling Engineer’, December 1891, p 184, cols 2 & 3. I have individually numbered each of the mills so as to make them more obvious.
Extract:- “The bakers are delighted with the action of the following sixteen firms who manufacture Hungarian flour and export it to England, namely
1.Concordia Steam Mill Co., Lim.;
2.Elizabeth Steam Mill Co.;
3.First Budapest Steam Mills Co., Lim. (Erste Ofen-Pester)
4.Gizella Steam Mills;
5.Henry Haggenmacher Steam Flour Mills, Budapest;
6.Louisa Steam Mill Co., Budapest (Hungary);
7.Pannonia Steam Flour Mills;
8.The Pesth Cylinder Flour Mill Co., Lim. (Pestihengermalom-társaság-Pester Walzmühl-Gesellschaft);
9.The Pester Millers and Bakers Steam Flour Mills Co., Lim., Budapest;
10.United Steam Mills of the Hungarian General Credit Bank;
11.”Victoria” Steam Mills, Budapest;
12.Losonczer und Hatvaner Dampfmühlen in Losoncz;
13.The Borsod Miskolcz Steam Flour Mill Co., Lim., in Miskolcz;
14.”István” Steam Mill Co., in Debreczen;
15.The Nagyvárad “Laszlo” Cylinder Flour Mill Co., Lim., in Nagyvárad;
16.The Szatmár Steam Mill Co., in Szatmár
who have reduced the number of their grades of flour and established a fresh standard, and in order to protect their new type flours they have as a body caused a conventional trade mark to be registered. The flour manufactured by the above named firms will consequently henceforth only be sold and supplied in sacks sealed with leads bearing the registered trade mark, which consists of the number of the grade of the flour surrounded by a triangle composed of three wheat ears on the side of which the letters M.T. are to be seen. The other side of the lead-seal is used to stamp the name of the firm who manufactured the flour.'
As this has no ear of wheat triangle and MT it must predate December 1891 when the article was published.