New Discovery! Rossetti's lost drawings of Swinburne?

Sometimes, a strange coincidence occurs. A few years ago, I bought a battered copy of The Bonchurch Edition, Letters, a volume of the Complete Works of Swinburne, 1927.

Loosely enclosed was a letter and a few photographs of drawings by Rossetti of Swinburne. I didn't overthink about them as I am not a fan of the drawing on Hutchings and Turley's "Young Life of Algernon Swinburne", which I hadn't read closely until recently.

On the first page, a rare image on the front cover is described. The image was intended for Rossetti's Early Italian Poets, 1861, but it wasn't used.

Here is a letter from 1956 that accompanied the photographs. The originals were sold to an American dealer, so I guess they are in America now.

Here are the sketches and a copy of the prototype finished drawing. I don't know how rare these are; perhaps someone can supply more information.

They look like one-off copies, and the sepia print is a print off the block.

Initial sketches and ideas for the plate.

Sketch before being made into a printing plate.

The final image is printed on thin card. Possibly one of only a few examples produced.