St Helena's fame during the Middle Ages was assured both by the historical circumstance that she was the mother of Constantine the Great, and also by the legendary attribution to her of the finding of the Cross on which Jesus was crucified. Through accretion, her status was further elevated: she was considered to have actively participated in the conversion of Constantine to Christianity and thereby to have played a considerable part in the recognition of Christianity as the dominant religion of the Roman Empire. These excellent credentials for renown span both the secular and religious spheres and must have been very appealing to a wide range of communities wishing to associate themselves with Helena or to appropriate her more directly for their own rhetorical and political purposes. In the context of her multifaceted value as Roman empress and Christian saint, there arose in England from Anglo-Saxon times a further cause for Helena's celebrity: the audacious claim that she was a native of Britain, in some cases the daughter of King Cole of Colchester (the ‘merry old soul’ of the nursery rhyme). For at least one thousand years, this legend of a noble, British birth was invoked, modified, and elaborated by writers of histories, chronicles, poetry, saints' calendars, and hagiography, depicted by visual artists, and kept alive as a tradition, both in England and abroad.

Typically of both legend and hagiography, the story of Helena developed some outlandish manifestations: Helena as disguised princess, Jewish convert, or Welsh dawn goddess. The form of the legend changed as often as the vehicle for transmission, and varied according to genre, audience, and circumstances. Because the story was contingent upon the immediate factors of reception for its shape and contents, there is no single legend, but rather a large number of constructions of the idea of a British princess Helena which served a variety of uses.