Hand illuminated & calligraphed poem on sheep's vellum

This is a poem titled Saint Gabriel that's illuminated and lettered by hand on sheep's vellum, and the illuminations may be done in egg tempera or gouache with some added fine metallic gold lines that may be ink.  The calligraphy is done in black ink.  The original cardboard backing that the vellum was mounted on bulged out so badly that the piece couldn't be hung flat upon a wall for display.  I remounted the vellum on archival board using archival glue, though I'm sure this devalued the piece.  The poem is in its original frame, but some of the gilt was worn and I did my best to repair it, as well.  The piece is rated as "good" because of the repairs, but the actual illuminations, calligraphy and vellum are in excellent condition.

There's no information online about the poem Saint Gabriel, and there's no way of knowing who created and signed the piece with the initials S. W.  It was purchased for $10.00 in a second hand store in the Fenway neighborhood of Boston back in the 1980s.  It may have been created during the Arts & Crafts movement which occurred from about 1860 through 1910.  It would be interesting to find out about its history.