Swan sued Edison in the UK, claiming patent infringement; this was upheld by the British courts.

Subsequently, in order to avoid uncertain and expensive litigation, the two companies negotiated a merger.

[4] From 1887 or earlier Sir Ambrose Fleming was an adviser to the company, and conducted research at Ponders End.

[5] The company had offices at 155 Charing Cross Road, London, and factories in Brimsdown, Ponders End and Sunderland.

In 1964, AEI merged its lamp and radio valve manufacturing interests with those of Thorn Electrical Industries to form British Lighting Industries Ltd.[1] Edison Swan (or later Siemens Edison Swan) produced a wide range of vacuum tubes and cathode ray tubes under the names "Ediswan" or "Mazda"[6] and the 1964 Mazda Valve Data Book claimed: "Professor Sir.