Joan, who is somewhere in her mid sixties, is Strike and Lucy‘s aunt by marriage. Their Uncle Ted, who is their mother’s brother, is married to Joan, and they live in St. Mawes in Cornwall in a “neat little house that smelled of flowers and baking.” Joan has apparently been in St. Mawes for much of her life — she was a schoolmate of Ilsa Herbert‘s mother, which is part of the reason that Cormoran and Ilsa form a friendship.
Aunt Joan and Uncle Ted have played a significant role in Strike and Lucy’s life as surrogate parents. It is at their home in St. Mawes that the brother and sister spent half their childhood, with their aunt and uncle frequently rescuing them from dicey situations in their mother’s itinerant lifestyle. They were even willing to drive all night from St. Mawes to London to collect their niece and nephew.
Despite Joan’s disapproval of Leda Strike‘s lifestyle (she apparently told Leda she would end up in hell), their aunt tried, “with diminishing success through the years, not to disparage their mother in front of the children.” At one point in The Cuckoo’s Calling, Lucy purses her lips in disapproval at Cormoran, and he observes that she bears “a strong resemblance to their Aunt Joan,” even though there was no blood relation. Aunt Joan was desperately disappointed when Strike dropped out of Oxford.
Aunt Joan has been responsible over the years for filling in family history for Strike where his mother had left off. It is from her that he learned the eighteen-year-old Leda had left her husband (the original Mr. Strike) after only two weeks; “that her sole motivation in marrying Strike Snr. (who, according to Aunt Joan, had arrived in St. Mawes with the fair) had been a new dress, and a change of name.”