IanC, thanks for posting. Yours is not exactly the 'original'?, but I think that as time went on, various editors added little improvements. I looked up Rose Alnora Hartwick Thorpe (1850-1939). Born in Indiana, grew up there and in Kansas and Michigan. In 1870, she submitted "Curfew Must Not Ring" to the "Commercial Advertiser" of Detroit. Newspapers spread it across the country and to England. This was already posted in Joe's notes from Hickerson with the Connor et al. version, I can't understand how Hickerson arrived at the conclusion that "Nellie" was not a parody of the teenage poem written by Hartwick (later married Thorpe, a carriage-maker). She also wrote children's fiction.
In 1887, her book, "Ringing Ballads, including Curfew Must Not Ring Tonight," was published by Lothrop in Boston. The book has been digitized and is at American Memory.

She also wrote "Remember the Alamo! The War-Cry at San Jacinto, Texas." This is available at the Women's History website.

For a brief biography and the original(?) of the Curfew poem, see the Women's History website:
Curfew Must Not

Mrs. Leslie Carter took the part of the heroine in Belasco's 1895 play, "Heart of Maryland." A scene in the play was based on Thorpe's poem, but I can't find any reference to the poem being sung.
Was the poem set to music before Beatrice Kay's time?. She performed in Canada and USA as well as in the UK. My mother, I remember, had a recording or two by her.