In his photography Thomas Keith used the waxed paper process developed by Gustave Le Gray (1820-1884), which he simplified and improved.
Keith's prints and negatives are held by a number of institutions including the Edinburgh Central Library, the Scottish National Portrait Gallery, the Royal Scottish Academy, the National Museum of Photography, Film and Television, the Canadian Centre for Architecture, George Eastman House, Harry Ransom Center [REF][REF][REF][REF] .