The pock-marked intruder was chewing on a cabbage leaf from my vegetable patch. There was no indication of how he had scaled the high wall, and I was certain that he had not come through the house, so it was a complete mystery as to how he had managed to gain entry to my garden.

As I asked the stranger about the purpose of his ‘visit’, I saw that the small spiral notebook in his left hand was opened on a page where three different spellings of ‘Haydon Bridge’ had been tested. I wondered if – rather than a former student or work colleague – this man might be a genealogical researcher.

I was right. He was pretty certain that we were connected to family D. When I told him emphatically that we were not, his face dropped. He has been hoping that we would be the final piece in the jigsaw to explain his deadly inherited disease.