For the last ten years I have been presenting historical programmes on television, and writing books to go with them. The most recent have been about what the Victorians and Tudors and Stuarts did for us, but the earlier programmes were about long-dead scientists and inventors; we called them Local Heroes.

Our starting point in looking for local heroes in a particular place was always the local history or local studies library. There we could be fairly sure to find both the information and the expertise to extract it. I remember making a phone call to the local-studies librarian in Perth and asking whether he had any suitable candidates. He said, “Would you be interested in Mr Gilbert Malloch, who invented the combined walking stick, camera tripod, salmon gaff, and landing net?” Sure enough, Gilbert Malloch became a local hero.