Rosemary Sutcliff once said about writing her Arthurian novel  Sword at Sunset – a bestseller in 1963:

… after I had finished the story I had great difficulty getting back into a woman’s skin, because I had been living as a man for eighteen months, thinking as a man, making love as a man, always looking from a man’s viewpoint. I am always deeply involved in my books. For me the book doesn’t work if I am not. But I have never been as deeply involved as that before or since.

When I started writing Sword at Sunset I made at least three false starts, but I couldn’t think what was the matter. I knew exactly what the story was that I wanted to tell, but it wouldn’t come. Then suddenly the penny dropped: it had to be first-person singular. I had never done first-person singular before, but the moment I started doing it that way it came, like a bird. But I had problems with it: first-person singular is very different from third-person writing, and I had no experience of it at all. But it was the only way it could be written.

• Source: Interview with Rosemary Sutcliff  by Raymond H Thompson (here, reproduced on this blog)