Stanley S. A. Watkins (1888-1975) George R. Groves (1901-1976) The British electrical engineers who worked in America for Western Electric and Warner Bros. and played major roles in the development of 'Talking Pictures'.

see http://www.amps.net/media/files/library/journals/20_December_1996_1.pdf"Brian Hickin of AMPS contacted Warners who undertook a thorough investigation. They reported that they’d sold their cinema chain, including their flagship Leicester Square cinema, to SBC International Cinemas in 2003, who’d re-branded them all as Vue. A re-development had taken place at the West End theatre, the plaque had been removed and it was never returned. No one knows where it is now, as Warners’ spokesman commented: “Unfortunately, we are unable to come up with any clues as to its whereabouts. Even searching in the out of the way nooks and crannies of the cinema has not yielded results.”" - http://www.georgegroves.org.uk/blog_files/george_groves_news_2009.html

See also...