Thomas Edison of the Edison patent to charge a more reasonable rate for the use of the Edison patent rights and lowering the price of the electric lamp. On October 8, 1883, the US patent office ruled that Edison's patent was based on the work of William E. Sawyer and was, therefore, invalid. Litigation continued for nearly six years, until October 6, 1889, when a judge ruled that Edison's electric light improvement claim for "a filament of carbon of high resistance" was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison's,
St. George Lane Fox-Pitt December 1879, Charles Francis Brush founded the Anglo American Electric Light Company Ltd. in the UK and then acquired the patent rights to produce the Lane-Fox incandescent lamp in the same year. On 24 March 1880, he founded a new company, Anglo-American Brush Electric Light Corporation, which took over the previous one. About 1880, Fox-Pitt is said to have successfully experimented with charred plant fibers as the filament material. That was about the same time as the development of the light bulb with carbon filament by Edison in the United States. By 1883, Fox-Pitt had obtained further patents. Fox-Pitt wrote