BBC L1 lip microphone, 1937-1960
1937-1960
1937-1960
1967
1922-1924
1986
circa 1962
1972
1960
1962
1979
1958
circa 1931
Unknown
1977
1970
1960
1969
1900-1930
1985
circa 1932
1938
circa 1948
1987
1966
1952
1985
1970-1979
1931