Year – 1950s. The Knitting and Crochet Guild has a scan of a booklet from 1954 which lists this exact yarn.
Size – 34, 35, 36 inch busts
Yarn Size – 4 stitches per inch, possibly DK but I can’t confirm this – A ball of Patons Beehive Bedjacket Floss is in a museum in Australia.
I sell this pattern in my online shop. Mine’s from 1940 and and says to use Beehive Non-shrink baby wool in 3-ply.