This paper explores the careers of several British women astronomers in the late nineteenth and early twentieth centuries. I postulate that the only category of scientific practice open to most of these women was that of an ‘amateur’. They would have become professionals had they had the opportunity but since they were barred from professional status they used their talents to promote the importance of amateur science. I propose the term ‘obligatory amateur’ for these women who, unlike men, were unable to choose amateur or professional status. I explore this concept of a ‘gendered’ amateurism through the life and works of Annie Maunder, with references to British women astronomers contemporary with her.