The significance of ?AD.FMSZ?, is said to be found by putting the name of Frodsham against numbers thus: F R O D S H A M Z 1 2 3 4 5 6 7 8 0 Hence FMSZ gives the date 1850. During the late 19th and early 20th century the firm was closely connected with Nicole Nielsen who made most of the movements, including some of the most perfect tourbillons ever made, and which still perform with almost unrivalled accuracy. At some time before the mid-20th century, the company began making lever escapement and chronometer escapement watches of the very highest quality and continued to do so until the outbreak of war in 1939. Frodsham watches are almost always elegant and well proportioned. Even as late as 1914, some of them, with engine-turned silver dials, were worthy of Breguet. The firm was appointed watchmaker to the King, The Prince of Wales, and to Queen Alexandra. They were responsible for maintenance and winding of all the clocks at Buckingham Palace, where they had a workshop. Frodsham's best cases were made by his son, Harrison Mill Frodsham (1849-1922), who took over the firm after his father death and proved to be an expert horologist.