1938 - 1953

Alec Lodge died

1939/45 - Invention of the 'S' alloy and the Thermo-Couple Plug.
The firm was registered as "an undertaking under the Essential Works Order." Plugs were produced for almost every kind of internal combustion engine - fitted in motor torpedo boats, landing craft, air-sea rescue launches, all varieties of military vehicle (including tanks) and stationary power equipment. Special adaptations of the sparking plug were also designed for flame-throwers. The majority of production, by far, was for the R.A.F. and the US Air Force, which between them absorbed seventy-five per cent of total production.

President Roosevelt in an address to Congress at the end of 1944 said:

"Reference is made to the British aircraft supplies to the Americans…….before and during the Battle of Britain, when the R.A.F. had to work its out-numbered planes around the clock and the Spitfire and Hurricane engines got punishing treatment, the British developed a new type airplane spark plug ….. Since early in 1943 virtually every United States Flying Fortress has taken off from British bases with these plugs in each of its four engines. It would be impossible to estimate how many thousand United States bomber crews may since then have owed their lives to these spark plugs, but the performance record of the plugs speaks for itself."

1948 - Product diversification with the introduction of Thread guides for the textile industry.

1949 - The shareholders elected to sell their interest, and Lodge Plugs Ltd. was floated as a public company. Mr. Brodie Lodge retired and Mr. Hopps became Chairman and Managing Director.

1949 to 1953 - every 500 c.c and ten other capacity class World Motor Cycle Championships were won by machines using Sintox and "S" Alloy spark plugs.