I'm thinking that if I had encountered almost any of the stories therein that I've read so far, and been asked to guess the writer, I'd have plumped for Neil Gaiman. There are a few differences, but mostly due to the era in which she was writing, which is probably the early 70s - late enough for decimalisation, but early enough for prices to be somewhat low by today's standards.
These are stories more for grown ups than for children, and I think that shows the problem that Aiken may have had: her most celebrated works are probably The Wolves of Willoughby Chase and its successors, which are set in an alternative history where the Hannoverians lost. They started to come out in the early to mid sixties, and for those of us that encountered them, they were some of the best children's literature of the time. I may have tried to read this book when it came out - if so, I think it would have deeply disappointed me, because I would not have got them at all. Hope for example, concerns a spinster central character with a love affair lost 30 years in the past. I suspect that Aiken got tagged as children's literature in a way that Gaiman hasn't, to the possible detriment of her more adult work.