I found it hard to believe that she hadn’t got a clue about her family history
Reading a few other articles on this programme it seems that Bill Humble spent most of his post-war life abroad, and only came home not long before his death. Seems he was not a very good father to Kate’s father (a serious womaniser, for a start, and perhaps fond of the bottle, too?), which suggests to me that there was not much contact. If her Dad was not that impressed with his father, it’s unlikely he told her much about the man, perhaps?
My late FiL was in Burma during the war, and we know very little about his time there, or before, when he was in an Army Commando, despite the fact that he only died 22 years ago, when my wife was 27. He just did not talk about it, and I suspect the same was true of KH’s maternal grandfather