Ingersolls patent (641072 - Ingersoll Ltd, L W Young & J W Taylor. - Improvements in Plug and Cylinder Type Mechanism) of 1946 was the first of many Ingersoll patents relating to key operated locks and represented a new post war direction.

Key registration was a feature which was seen as both a security enhacement and a marketing advantage perfectly complimenting each other. However the means of producing the key differs was a very closly guarded secret from the very begining. Even today the replacement key business is not insignificant.

Jack Taylor put in place a number of safeguards, one internal memo that was issued in 1946:-

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Ingersoll is a particularly interesting company to us, the archives contain a huge amount of material collected over the years, documents, drawings and artefacts etc. which we can draw on to explore and illustrate the company history in response to the discussions in this thread.